Modern healthcare relies on imaging modalities that visualize internal anatomy and pathology. While X-ray computed tomography (CT) and magnetic resonance imaging (MRI) provide clinically useful imaging across many applications, they face significant barriers to more frequent use: ionizing radiation limits repeated CT scanning, and MRI\u2019s high cost and long acquisition times create access disparities. Conventional handheld ultrasonography enables rapid, low-cost imaging but remains limited by narrow fields of view, operator dependence, and challenging image interpretation. Photoacoustic tomography has emerged as a promising alternative that combines optical absorption contrast with acoustic detection, offering molecular specificity without ionizing radiation. However, conventional photoacoustic imaging remains limited to depths of several centimeters, inhibiting applications in deep-tissue imaging like gastrointestinal or whole-body assessment.
\r\n\r\nIn this thesis, we develop three approaches to extract clinically relevant information at human scales: ultrasound, thermoacoustic, and photoacoustic tomography. All three modalities leverage a custom 512-element, 60 cm diameter receiver array designed to detect acoustic signals across human-scale geometries. We validate these approaches through in vivo imaging, ex vivo tissue experiments, and phantom studies. First, we demonstrate ultrasound tomography of full human cross-sections in the abdomen and lower extremities, reconstructing backscatter contrast alongside quantitative maps of the speed of sound and attenuation coefficient. We show that ultrasound tomography enables visualization of features such as the liver, vasculature, muscle, and subcutaneous adipose across entire 2D human cross-sections. Second, we develop a thermoacoustic approach to guiding microwave ablation procedures. By modulating the microwave signal delivered through the probe, we record the generated thermoacoustic signals and use them to model the thermal dynamics during ablation. We show that this approach yields more accurate estimates of ablation zone geometry than standard look-up tables, which could allow for more precise ablation therapy. Third, we develop a method to extend the imaging depth of photoacoustic tomography using a wireless, ingestible capsule-based optical source. We demonstrate imaging depth up to 12 cm, which could open the door to photoacoustic imaging of regions like the gastrointestinal tract. Together, these approaches aim to expand the range of safe, informative, and accessible imaging modalities available to patients and clinicians.
", "doi": "10.7907/s8t2-qb10", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:18457", "collection": "thesis", "collection_id": "18457", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03302026-100637929", "primary_object_url": { "basename": "Enabling_Technologies_and_Algorithms_for_Antenna_Arrays.pdf", "content": "final", "filesize": 47465358, "license": "other", "mime_type": "application/pdf", "url": "/18457/2/Enabling_Technologies_and_Algorithms_for_Antenna_Arrays.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Enabling Technologies and Algorithms for Antenna Arrays", "author": [ { "family_name": "Wu", "given_name": "Ailec", "orcid": "0009-0008-7726-7842", "clpid": "Wu-Ailec" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hassibi", "given_name": "Babak", "orcid": "0000-0002-1375-5838", "clpid": "Hassibi-B" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Abu-Mostafa", "given_name": "Yaser S.", "clpid": "Abu-Mostafa-Y-S" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Phased arrays provide high angular resolution, efficient spatial power combining, and dynamic electronic beam-steering; although there are many applications of phased arrays, there are considerable challenges in their realization. This thesis summarizes the author's work in developing a novel phased array calibration method to address timing and synchronization challenges in phased arrays, as well as work exploring the usage of phased arrays in wireless power transfer in the context of the Caltech Space Solar Power Project. First, the calibration method is described, which involves usage of amplitude-only sensor placed in the proximal field of the array's radiators: to obtain array phase information from these sensors, machine learning is used to solve the phase retrieval problem generated from sensor raw data. Then the satellite payload producing the first in-orbit wireless power transfer demonstration is described. Finally, a method to address areal power matching issues between photovoltaic and wireless power transfer subsystems is described.", "doi": "10.7907/wram-da27", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:18457", "collection": "thesis", "collection_id": "18457", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03302026-100637929", "primary_object_url": { "basename": "Enabling_Technologies_and_Algorithms_for_Antenna_Arrays.pdf", "content": "final", "filesize": 47465358, "license": "other", "mime_type": "application/pdf", "url": "/18457/2/Enabling_Technologies_and_Algorithms_for_Antenna_Arrays.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Enabling Technologies and Algorithms for Antenna Arrays", "author": [ { "family_name": "Wu", "given_name": "Ailec", "orcid": "0009-0008-7726-7842", "clpid": "Wu-Ailec" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hassibi", "given_name": "Babak", "orcid": "0000-0002-1375-5838", "clpid": "Hassibi-B" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Abu-Mostafa", "given_name": "Yaser S.", "clpid": "Abu-Mostafa-Y-S" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Phased arrays provide high angular resolution, efficient spatial power combining, and dynamic electronic beam-steering; although there are many applications of phased arrays, there are considerable challenges in their realization. This thesis summarizes the author's work in developing a novel phased array calibration method to address timing and synchronization challenges in phased arrays, as well as work exploring the usage of phased arrays in wireless power transfer in the context of the Caltech Space Solar Power Project. First, the calibration method is described, which involves usage of amplitude-only sensor placed in the proximal field of the array's radiators: to obtain array phase information from these sensors, machine learning is used to solve the phase retrieval problem generated from sensor raw data. Then the satellite payload producing the first in-orbit wireless power transfer demonstration is described. Finally, a method to address areal power matching issues between photovoltaic and wireless power transfer subsystems is described.", "doi": "10.7907/wram-da27", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:17769", "collection": "thesis", "collection_id": "17769", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:11182025-233532194", "type": "thesis", "title": "Energy Efficient On-Chip Neural Feature Extraction for Brain-Computer-Interfaces", "author": [ { "family_name": "Bulfer", "given_name": "Steven Patrick", "orcid": "0000-0001-9942-1195", "clpid": "Bulfer-Steven-Patrick" } ], "thesis_advisor": [ { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" } ], "thesis_committee": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Pedroni", "given_name": "Volnei A.", "clpid": "Pedroni-Volnei-Antonio" }, { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Neural interfaces are entering an era where what once was science fiction is becoming a reality. As neural interfaces move out of the lab and into people's lives, the stability of neural decoding algorithms becomes ever more pressing. It is an unfortunate reality that neural implants degrade from long-term exposure to the neurological environment, however prior work has shown enhanced decoding stability in the application of 1D convolutional neural networks to neural feature extraction. However, these algorithms have high memory and processing requirements, prohibiting them from meeting the low area and power restrictions of implantable brain-machine interface decoding pipelines.
\r\n\r\nThis dissertation addresses the difficulties of implementing these algorithms on streamed neural data with high parallelism and low area and power costs. We address the unique dataflow characteristics of the feature extraction workload by designing a tailored processing element that reduces the memory access requirements by 2x. We further reduce system memory requirements through efficient process scheduling and memory partitioning. We then address the model complexity through retraining and analysis of the effect of various system parameters on the accuracy of kinematic decoding and hardware performance.
\r\n\r\nResults show that these design choices were able to successfully implement these intensive but performant algorithms within the power and area budgets of implantable devices. The architecture supports 192 channels that achieve state-of-the-art decoding stability at 1.8 uW and 12801 um^2 per channel in 65 nm CMOS technology. The device is a fully configurable, scalable, area and power efficient solution that supports models with 2-8 feature layers and a total kernel length of up to 256. This architecture reduces caching requirements by 5x over conventional computation schemes. We show our hardware optimized models maintain superior stability over time using recorded data from tetraplegic human participants with spinal cord injury. The models and hardware were validated in real time with a human subject in online closed-loop center-out cursor control experiments with micro-electrode arrays that were implanted for 6 years. Decoders using features generated with this work substantially improve the viability of long-term neural implants compared to other feature extraction methods currently present in low-power BMI hardware.
", "doi": "10.7907/40as-d020", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:18476", "collection": "thesis", "collection_id": "18476", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04072026-143808452", "type": "thesis", "title": "Scalable Arrays From Millimeter-Wave Sensing to Microwave Wireless Power Transfer", "author": [ { "family_name": "Ayling", "given_name": "Alex Eben", "orcid": "0009-0008-5440-7785", "clpid": "Ayling-Alex-Eben" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Yang", "given_name": "Changhuei", "orcid": "0000-0001-8791-0354", "clpid": "Yang-Changhuei" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Siegel", "given_name": "Peter H.", "orcid": "0000-0002-2539-4646", "clpid": "Siegel-P-H" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Wireless power transfer at a distance, long relegated to the realm of science fiction, has seen a resurgence in recent years. Chief among its promises is Space-Based Solar Power (SBSP), an ambitious project to deploy kilometer scale photovoltaic arrays in space and beam its power down to Earth using a complementary microwave phased array. The building blocks of the array are phased array tiles, which can be instantiated to produce larger apertures.
\r\n\r\nThe tile must be simultaneously lightweight and flexible for deployment in space, low-cost, high-performance, and scalable. First, the results of the MAPLE mission, which tested wireless power transfer in space using custom flexible arrays, are presented. Using the results of that mission, the design and testing of next-generation, fully flexible 8x8 element phased array tile are presented. The tile is driven by a custom 22-nm CMOS FDSOI RFIC that achieves record efficiency and performance. These results represent not only a step forward toward practical microwave wireless power transfer but offer new directions in communications and sensing driven by flexible arrays.
\r\n\r\nAdditionally, topics on maximum power point tracking in SBSP systems, transmitarrays for SBSP, and the design of a fully-integrated, scalable, and low-cost D-band (110-170GHz) radiator tile are discussed.
", "doi": "10.7907/w440-k235", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:18479", "collection": "thesis", "collection_id": "18479", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04072026-222438150", "type": "thesis", "title": "Flexible Phased Arrays: Challenges & Opportunities", "author": [ { "family_name": "Mizrahi", "given_name": "Oren Simon", "orcid": "0000-0003-4271-8822", "clpid": "Mizrahi-Oren-Simon" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Pellegrino", "given_name": "Sergio", "orcid": "0000-0001-9373-3278", "clpid": "Pellegrino-S" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Chandrasekaran", "given_name": "Venkat", "clpid": "Chandrasekaran-V" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The history of technological progress can be seen through the lens of an interplay between utility and form factor: new applications inspire and/or demand new form factors, which in turn enable new applications, etc. This has long been the trajectory of antenna systems and phased arrays, which have scaled in form factor and broadened in adoption over the last century. Phased arrays currently straddle two regimes: highly scaled down for portable device compatibility or scaled up for array gain and complex functionality. Flexible phased arrays may be the next form factor to enable new applications: space solar power generation, high-bandwidth satellite communications, and others. However, challenges imposed by an array's flexibility, including radiator design, phase synchronization, and demonstrated viability, hinder the widespread adoption of flexible phased arrays. This thesis offers solutions to these challenges and discusses the opportunities flexible phased arrays offer for the future.", "doi": "10.7907/2bt7-3961", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:18730", "collection": "thesis", "collection_id": "18730", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06012026-040226100", "type": "thesis", "title": "Information Technologies at the Fundamental Physical Limits", "author": [ { "family_name": "Gurses", "given_name": "Baris Volkan", "orcid": "0000-0001-8184-208X", "clpid": "Gurses-Baris-Volkan" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Vahala", "given_name": "Kerry J.", "orcid": "0000-0003-1783-138", "clpid": "Vahala-K-J" }, { "family_name": "Mirhosseini", "given_name": "Mohammad", "orcid": "0000-0002-9084-6880", "clpid": "Mirhosseini-M" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Fundamental physical laws dictate the performance bounds of all technologies. Over the last century, advances in nanotechnology and integrated circuits have driven the performance of communications, sensing, and computing toward these bounds. As scaling continues, classical limits are increasingly constraining further improvements. The advent of quantum technologies opens paths to overcoming some of these constraints and to building technologies that operate at the fundamental physical limits. This thesis develops a unified framework for these limits and demonstrates large-scale integrated photonic-electronic systems that approach them. In sensing, quantum phased arrays\u2014coherent antenna arrays that transmit or receive quantum fields over free space\u2014are introduced and demonstrated with up to 32 elements for squeezed light imaging, beamforming and beamsteering, overcoming the standard quantum limit to approach the Heisenberg limit and enabling protocols for free-space quantum sensing, quantum communications, and quantum information processing. In communications, quantum coherent transceivers are introduced and demonstrated that transmit and receive non-classical light to surpass the Shannon limit and approach the Holevo limit. In computing, large-scale crosstalk-corrected thermo-optic phase shifter arrays and a 256-element programmable photonic mesh are demonstrated, addressing the scaling challenges of integrated photonic-electronic processors. For each system, I present the underlying theory, design, experiments, and applications, and outline a vision for how these technologies can be practically deployed in the future.", "doi": "10.7907/qhb7-ew96", "publication_date": "2026", "thesis_type": "phd", "thesis_year": "2026" }, { "id": "thesis:17366", "collection": "thesis", "collection_id": "17366", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06022025-173123134", "primary_object_url": { "basename": "shila_kiran_2025_FINAL.pdf", "content": "final", "filesize": 35013874, "license": "cc_by_nc_sa", "mime_type": "application/pdf", "url": "/17366/1/shila_kiran_2025_FINAL.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Low Noise at Low Cost for Large Radio Astronomy Arrays", "author": [ { "family_name": "Shila", "given_name": "Kiran Arik", "orcid": "0000-0003-4652-7038", "clpid": "Shila-Kiran-Arik" } ], "thesis_advisor": [ { "family_name": "Hallinan", "given_name": "Gregg W.", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G-W" }, { "family_name": "Padin", "given_name": "Stephen", "orcid": "0009-0001-9993-4393", "clpid": "Padin-Stephen" } ], "thesis_committee": [ { "family_name": "Ravi", "given_name": "Vikram", "orcid": "0000-0002-7252-5485", "clpid": "Ravi-Vikram" }, { "family_name": "Hallinan", "given_name": "Gregg W.", "orcid": "0000-0002-7083-4049", "clpid": "Hallinan-G-W" }, { "family_name": "Padin", "given_name": "Stephen", "orcid": "0009-0001-9993-4393", "clpid": "Padin-Stephen" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Bouman", "given_name": "Katherine L.", "orcid": "0000-0003-0077-4367", "clpid": "Bouman-K-L" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The 2020s is the decade of survey instruments in astronomy. Radio astronomy is no exception, with Caltech's proposed DSA-2000 being the most powerful radio interferometer in the world, costing much less than competing instruments. Key to this achievement are two core breakthroughs: a completely ambient-temperature receiver and a \u201cradio camera\u201d backend that images the sky in real time. DSA-2000 will have record-breaking survey speed and sensitivity, enabled by these two key breakthroughs, giving astronomers all over the world open access to exquisite all-sky maps to enable the discovery of billions of new radio sources, precise timing of pulsars, and localization of fast radio bursts. The array will produce enough data to keep astronomers busy for a century.
\r\n\r\nIn this thesis, we discuss the development of one of the key breakthroughs, the ambient-temperature receiver. Specifically, we focus on the design, testing, and implementation of the wideband, ambient-temperature low noise amplifier. We cover the design from analytic first principles through precision measurement of its performance. We follow this with a discussion of the design and implementation of the analog signal path, including a high performance, RF over fiber link. Finally, we discuss the Galactic Radio Explorer (GReX) instrument, designed as a global experiment probing the brightest radio transients in the local universe.
", "doi": "10.7907/ng6s-6484", "publication_date": "2025", "thesis_type": "phd", "thesis_year": "2025" }, { "id": "thesis:16192", "collection": "thesis", "collection_id": "16192", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:09272023-180554728", "primary_object_url": { "basename": "Ives_Craig_2024.pdf", "content": "final", "filesize": 145161062, "license": "other", "mime_type": "application/pdf", "url": "/16192/1/Ives_Craig_2024.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Subtractive Photonics in Bulk CMOS", "author": [ { "family_name": "Ives", "given_name": "Craig Edward", "orcid": "0009-0006-3893-541X", "clpid": "Ives-Craig-Edward" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Yang", "given_name": "Changhuei", "orcid": "0000-0001-8791-0354", "clpid": "Yang-Changhuei" }, { "family_name": "Sideris", "given_name": "Constantine", "orcid": "0000-0002-3042-4889", "clpid": "Sideris-Constantine" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Much of humanity's technological advancement over the last few decades may be attributed to exponentially increasing computing power, the bedrock of which is bulk CMOS technology. Exponentially increasing data rates in communications have also played an important role, facilitated by advancements in fiber optics and integrated photonics. However, efforts to capitalize on the complementary strengths of these two domains by merging them, an idea first envisioned almost 40 years ago, have so far proven inadequate. All previous attempts to integrate photonics in bulk CMOS have required either expensive process modification or resulted in waveguides with high loss.
\r\n\r\nIn this thesis, we discuss our investigations of a new method of integrating photonics into bulk CMOS, which we call the method of subtractive photonics. This method entails forming waveguides out of the back-end interconnect of an electronic chip. The interconnect metal is designed to wrap around dielectric channels such that when the metal is etched away, suspended dielectric waveguides remain. Although this method introduces a large, previously untapped design space, since there are many interconnect layers that can be used in photonic structures, it also introduces certain severe constraints. This thesis explores some of the possibilities this design space opens up, as well as some of the challenges involved in designing photonics in a process intended only for electronics. As part of this exploration, we demonstrate waveguides with an upper bound on loss that is significantly lower than the best previously published waveguide loss for unmodified bulk CMOS. We also demonstrate the first measurements of waveguide loss at visible and near-visible wavelengths in unmodified bulk CMOS, as well as the first measurements of waveguide coupled photodiodes in unmodified bulk CMOS. These proof-of-concept results may pave the way towards fully integrated electronic-photonic systems in unmodified bulk CMOS.
", "doi": "10.7907/yrz7-ds33", "publication_date": "2024", "thesis_type": "phd", "thesis_year": "2024" }, { "id": "thesis:16109", "collection": "thesis", "collection_id": "16109", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06122023-184556858", "primary_object_url": { "basename": "Thesis - Arian Hashemi Talkhooncheh - 2022.pdf", "content": "final", "filesize": 10208379, "license": "other", "mime_type": "application/pdf", "url": "/16109/1/Thesis - Arian Hashemi Talkhooncheh - 2022.pdf", "version": "v8.0.0" }, "type": "thesis", "title": "Holistic Design in High-Speed Silicon Photonics and Low-Power Electronics Platforms", "author": [ { "family_name": "Hashemi Talkhooncheh", "given_name": "Arian", "orcid": "0000-0001-8946-5047", "clpid": "Hashemi-Talkhooncheh-Arian" } ], "thesis_advisor": [ { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" } ], "thesis_committee": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Scherer", "given_name": "Axel", "orcid": "0000-0002-2160-9064", "clpid": "Scherer-A" }, { "family_name": "Zilkie", "given_name": "Aaron", "orcid": "0000-0002-4114-2297", "clpid": "Zilkie-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "High-speed interconnects are of vital importance to the operation of high-performance computing and communication systems, determining the ultimate bandwidth or data rates at which the information can be exchanged. Optical interconnects and the employment of high order modulation formats are considered as the solutions to fulfilling the envisioned speed and power efficiency of future interconnects. One area of growing importance in optical interconnects is the design and optimization of energy-efficient transmitters with superior power efficiency. Enhancing the electro-optical bandwidth density while keeping the power efficiency optimized, requires improvement in the optical power penalty of photonic integrated circuits. Moreover, co-optimization of electronics and photonics enables a path towards sub-pJ/b transmission efficiency. In this dissertation, architectural and circuit-level energy-efficient techniques serving these goals are presented.\r\n\r\nFirst, an integrated DAC-less PAM-4 transmitter in a multi-micron silicon photonics platform using 2 binary-driven uneven-length SiGe EAMs in an unbalanced MZI is presented. The optical transmitter exhibits 5.5dB ER at 100 Gb/s with 2.1dB SNR improvement compared to single EAMs driven by PAM-4 signals. Also, A DAC-less 200Gb/s QAM-16 transmitter in a multi-micron silicon-photonics platform using 4 binary-driven SiGe EAMs in an unbalanced MZI is presented. The transmitter exhibits bit-error rates of 3\u00d710-4 and 2.8\u00d710-4 for square and hexagonal constellations.\r\n\r\nSecond, a 100Gb/s PAM4 optical transmitter system implemented in a 3D-integrated Silicon Photonics-CMOS platform is presented. The photonics chip includes a push-pull segmented Mach-Zehnder Modulator (MZM) structure using highly capacitive (415fF to 1.1pF), yet optically efficient (V\u03c0L= 0.8 V.cm) metal-oxide-silicon capacitor (MOSCAP) phase modulators. Two pairs of U-shaped modulator segments with effective lengths of 170\u00b5m and 450\u00b5m are driven at 50 Gbaud by a dual-channel 28nm CMOS driver, which is flip-chip bonded to the photonics chip. The driver cores utilize digitally controllable pre-distortion and inductive peaking to achieve sufficient electro-optical bandwidth. The drivers deliver 1.2Vppd swing to modulators using a 0.9V supply and on-chip serializers that generate 50Gb/s data streams. The electronics chip consumes 240mW achieving 2.4pJ/bit energy efficiency. The overall electro-optical bandwidth (EOBW), without any pre-distortion, is increased by approximately 56% and 48% for the 170\u00b5m and 450\u00b5m segments, respectively, when compared to their EOBW measured by 65GHz 50-Ohm terminated probes. The optical input power to the photonics chip is +10dBm and an erbium-doped fiber amplifier amplifies output signals by 11dB. The 50Gb/s NRZ optical raw eye diagram exhibits 4.3dB extinction ratio (ER) and 1.2dBm of optical modulation amplitude (OMA). The 100Gb/s PAM4 optical raw eye diagram shows 4.3dB ER and 1.4dBm OMA with a transmitter dispersion eye closure quaternary (TDECQ) of 1.53dB after a 5-tap feed-forward-equalization (FFE) filter. The PAM4 TDECQ changes by 53% when the temperature is increased from 30\u00baC to 90 \u00baC at the optimum forward bias voltage of 1V.\r\n\r\nThird, an efficient cold-starting energy harvester system, fabricated in 65nm CMOS is presented. The proposed harvester uses no external electrical components and is compatible with biofuel-cell voltage and power ranges. A power-efficient system architecture is proposed to keep the internal circuitry operating at 0.4V while regulating the output voltage at 1V using switched-capacitor DC-DC converters and a hysteretic controller. A startup enhancement block is presented to facilitate cold startup with any arbitrary input voltage. A real-time on-chip 2D maximum power point tracking with source degradation tracing is also implemented to maintain power efficiency maximized over time. The system performs cold startup with a minimum input voltage of 0.39V and continues its operation if the input voltage degrades to as low as 0.25V. Peak power efficiency of 86% is achieved at 0.39V of input voltage and 1.34\u03bcW of output power with 220nW of average power consumption of the chip. The end-to-end power efficiency is kept above 70% for a wide range of loading powers from 1\u03bcW to 12\u03bcW. The chip is integrated with a pair of lactate biofuel-cell electrodes with 2mm of diameter on a prototype printed circuit board (PCB). Integrated operation of the chip with the electrodes and a lactate solution is demonstrated.", "doi": "10.7907/8yj9-2a62", "publication_date": "2023", "thesis_type": "phd", "thesis_year": "2023" }, { "id": "thesis:15205", "collection": "thesis", "collection_id": "15205", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05242023-033922764", "primary_object_url": { "basename": "Luis_Ledezma_thesis_2023.pdf", "content": "final", "filesize": 19438472, "license": "other", "mime_type": "application/pdf", "url": "/15205/1/Luis_Ledezma_thesis_2023.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Towards Universal Integrated Laser Sources with Nonlinear Photonics", "author": [ { "family_name": "Ledezma", "given_name": "Luis M.", "orcid": "0000-0002-0365-1672", "clpid": "Ledezma-Luis-M" } ], "thesis_advisor": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Vahala", "given_name": "Kerry J.", "orcid": "0000-0003-1783-1380", "clpid": "Vahala-K-J" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Lasers are ubiquitous in modern technology with different applications typically requiring different laser wavelengths. However, a given laser can operate only in a relatively narrow spectral region given by the particular material used to build the laser. This leads to using several lasers when several wavelengths are required. Nonlinear photonic devices pose a solution to this problem by transferring energy from single lasers to vast regions of the electromagnetic spectrum. But, despite more than 60 years of development in nonlinear photonics, most nonlinear devices remain large, expensive, and confined to research laboratories.
\r\n\r\nIn this dissertation, we demonstrate a new generation of integrated nonlinear photonic devices based on the quadratic \u03c7(2) nonlinearity. Using the up-and-coming thin-film lithium niobate platform, we demonstrate ultrafast optical parametric amplifiers, parametric generation of ultrashort mid-infrared pulses, long pulses and frequency combs tunable over an octave bandwidth, and the first \u03c7(2) CW parametric oscillator directly pumped by a single commercial diode laser. These results represent key milestones towards compact and inexpensive universal laser sources.
", "doi": "10.7907/ag5t-r511", "publication_date": "2023", "thesis_type": "phd", "thesis_year": "2023" }, { "id": "thesis:14491", "collection": "thesis", "collection_id": "14491", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02092022-003219315", "type": "thesis", "title": "Future Microwave Arrays Take Shape", "author": [ { "family_name": "Fikes", "given_name": "Austin Covey", "orcid": "0000-0003-4889-5782", "clpid": "Fikes-Austin-Covey" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Pellegrino", "given_name": "Sergio", "orcid": "0000-0001-9373-3278", "clpid": "Pellegrino-S" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Phased arrays provide high gain electronically steerable beams and are powerful systems for sensing and communication. Existing phased arrays are typically small, rigid, and planar which limits their possible use cases. This thesis describes the author's contributions to the creation of novel phased array architectures which can enable new phased array systems and applications. The first chapter describes the design, testing, and use of the scalable router. Scalable routers are a time delay array relay used to reroute signals a microwave frequencies. The second chapter describes the development of large scale flexible phased arrays, first in the context the Caltech Space Solar Power Project, and then in an exploration of a technique for determining the shape of arrays using only mutual coupling between elements. Finally, a guide for developing electronics for academic space payloads is included as an appendix.
", "doi": "10.7907/h541-3e28", "publication_date": "2022", "thesis_type": "phd", "thesis_year": "2022" }, { "id": "thesis:14536", "collection": "thesis", "collection_id": "14536", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03312022-192034489", "primary_object_url": { "basename": "D_Elliott_Williams_Doctoral_Thesis_Shape_Changing_Phased_Arrays.pdf", "content": "final", "filesize": 107493311, "license": "other", "mime_type": "application/pdf", "url": "/14536/15/D_Elliott_Williams_Doctoral_Thesis_Shape_Changing_Phased_Arrays.pdf", "version": "v12.0.0" }, "type": "thesis", "title": "Shape-Changing Phased Arrays", "author": [ { "family_name": "Williams", "given_name": "David Elliott", "orcid": "0000-0002-6213-4712", "clpid": "Williams-David-Elliott" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" }, { "family_name": "Bhattacharya", "given_name": "Kaushik", "orcid": "0000-0003-2908-5469", "clpid": "Bhattacharya-K" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Historically, increasing the degrees of freedom in electromagnetic structures has revolutionized the capabilities of wireless systems and introduced new applications. While research on phased arrays has explored everything from antenna drive settings to the element placement, the array geometry is assumed to be a fixed parameter. This thesis summarizes the author's work developing shape-changing phased arrays. It demonstrates the fundamental trade-off between gain and steering range for a given geometry. Measurements of the first shape-changing phased array both verify this theory and demonstrate the ability to break this trade-off using geometric reconfiguration. In addition, the mathematical consequences of shape-change and their impact on the arrays electromagnetic properties are discussed. Programmable passive switching networks on flexible sheets embedded in the array are proposed to address these challenges. The ability of these structures to enhance array performance is demonstrated by in-situ optimization experiments on a demonstration array. The associated optimization problem is characterized with a statistical analysis on a simulated array. Finally, avenues for further research are proposed.
", "doi": "10.7907/r6f1-zq65", "publication_date": "2022", "thesis_type": "phd", "thesis_year": "2022" }, { "id": "thesis:14578", "collection": "thesis", "collection_id": "14578", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05142022-060038327", "type": "thesis", "title": "Photovoltaic Technologies Developed for Space-Based Solar Power", "author": [ { "family_name": "Loke", "given_name": "Samuel Pei Hao", "orcid": "0000-0003-1856-3605", "clpid": "Loke-Samuel- Pei-Hao" } ], "thesis_advisor": [ { "family_name": "Atwater", "given_name": "Harry Albert", "orcid": "0000-0001-9435-0201", "clpid": "Atwater-H-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Goddard", "given_name": "William A., III", "orcid": "0000-0003-0097-5716", "clpid": "Goddard-W-A-III" }, { "family_name": "Minnich", "given_name": "Austin J.", "orcid": "0000-0002-9671-9540", "clpid": "Minnich-A-J" }, { "family_name": "Atwater", "given_name": "Harry Albert", "orcid": "0000-0001-9435-0201", "clpid": "Atwater-H-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "In this thesis, photovoltaic technologies were developed for space-based solar power. Two methods of realizing SBSP were introduced, namely concentrated photovoltaics (CPV) and radiation hard flat panel photovoltaics. Both techniques are instrumental to realizing SBSP as they are pathways to realizing high specific power and lower launch costs. Technologies developed to support these two forms of SBSP were then reported.
\r\n\r\nIn support of CPV, ultralight broadband mid-infrared coatings were developed for the concentrating mirrors used in our project. This was done to create radiative pathways for heat loss to ensure that the solar cells do not overheat. Using the rigorous coupled wave analysis technique, we optimized a backside single-layer coating using 2nm Cr/ 2\u03bcm CP1/ 500nm Ag that had an mIR emissivity of 0.6. Adding a second layer of this coating, we predicted that a 0.5nm Cr/ 1.9\u00b5m CP1/ 3nm Cr/ 2\u00b5m CP1/ 500nm Ag screen could achieve an emissivity of 0.8. We also optimized a 10nm ITO/ 2 \u03bcm CP1/ 500nm Ag frontside emitter which had a visible reflectivity of 0.896 and a mIR emissivity of 0.554. A backside emitter coating that was 0.927 emissive in the mIR with areal density 6.0 gm\u207b\u00b2 was successfully fabricated, as was a frontside mirror emitter coating with visible reflectivity of 0.896 and a mIR emissivity of 0.582 with areal density 4.1 gm\u207b\u00b2.
\r\n\r\nIn support of radiation hard photovoltaics, organo-lead halide perovskites (OHLP) were investigated. Challenges facing their fabrication were explored, with special focus on the electron transport layer PCBM as well as OHLP formulation. It was found that doping PCBM with a surfactant CTAB was beneficial, but did not work with all surfaces. An ITO/NiOx/MAPbI3/CTAB+PCBM/Cu device with in-house champion efficiency of 12.41% was achieved, and an ITO/NiOx/FA0.85Cs0.15PbI3/PCBM/Cu device with in-house champion efficiency of 11.81% was achieved. Time-dependant drift diffusion modelling was employed to account for the S-kink arising from poor PCBM carrier concentration.
\r\n\r\nFinally, the proton degradation of OHLP devices and constituent transport layers were investigated to shed better light on how OHLP devices degrade under proton irradiation. Films of ITO, PEDOT, NiOx, PCBM, and PTCDi were found to degrade under 30keV and 75keV protons of up to 1.4 x 10\u00b9\u2074 p\u207acm\u207b\u00b2 fluence, but their electrical resistivity and optical transmissivity were not found to impact the cell as much as the OHLP absorber layer itself. Observing the light IV and EQE degradation of OHLP cells, it is evident that proton deposition in the OHLP layer itself causes the most damage, especially at 30keV and 75keV protons with fluences from 4.3 x 10\u00b9\u00b3 p\u207acm\u207b\u00b2 to 1.7 x 10\u00b9\u2074 p\u207acm\u207b\u00b2. By considering the discrepancy in trends between Jsc and EQE, we concluded that the protons much accelerate intensity-based metastable photodegradation. Finally, by observing their anneal recovery, we concluded that it was temperature dependant and that maximum irrecoverable damage occurs at the OHLP/HTL interface.
", "doi": "10.7907/6jhy-2623", "publication_date": "2022", "thesis_type": "phd", "thesis_year": "2022" }, { "id": "thesis:14371", "collection": "thesis", "collection_id": "14371", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:09242021-181127485", "type": "thesis", "title": "High Sensitivity Time-Varying Systems In Photonics and Electronics", "author": [ { "family_name": "Porsandeh Khial", "given_name": "Parham", "orcid": "0000-0002-3242-8541", "clpid": "Porsandeh-Khial-Parham" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Yang", "given_name": "Changhuei", "orcid": "0000-0001-8791-0354", "clpid": "Yang-Changhuei" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Integrated electronics and photonics have been revolutionizing our daily lives for decades. However, the demand for high-speed communications, low-latency networks, and high-performance optical and electrical sensors continues to grow. In order to keep up with this demand as well as be able to address upcoming and unknown challenges, we need to explore unconventional solutions. Moving away from existing systems and traditional architectures allows us to take a deeper look at these challenges and potentially come up with nontrivial answers. In this thesis, unconventional approaches to implementing high-performance optical and electrical sensors and systems are investigated. Among these unorthodox solutions are time-varying architectures which led to completely new devices, sensors with dramatically improved sensitivity, and the breaking of known trade-offs.
\r\n\r\nBy developing a time-varying method that we call reciprocal sensitivity enhancement, we demonstrated a nanophotonic optical gyroscope (NOG) for the first time. The efficacy of this method is borne out by its ability to improve the performance of optical gyroscopes by two orders of magnitude. This sensitivity-enhancement method filters out reciprocal imperfections and noise, thereby increasing the overall signal-to-noise ratio. Next, the same approach is used to boost the performance of resonance-based magnetic biosensors. By merging two biosensors and taking advantage of the frequency response of magnetic beads, time-division switching cancels out most of the correlated noise. This solution pushes the sensitivity of this sensor below parts-per-million (PPM) levels for long periods of time \u2014 a property which is desirable in many biosensing applications.
\r\n\r\nAdditionally, an electrical scalable router that mitigates line-of-sight issues in next-generation wireless systems is introduced. This novel design does not require any shared timing reference to form a coherent array and uses a time-varying baseband to create a proper true-time delay. Next, we discuss how radiating elements in silicon-photonics platforms can be engineered to create a passive lensless camera. By applying a robust reconstruction algorithm, the captured image can be faithfully recovered. The same concept can be used in multi-mode nanophotonic antennas to alleviate the field-of-view (FOV)-aperture trade-off.
\r\n\r\nFinally, a hybrid photonic transmitter/receiver architecture, an electrical full-duplex transceiver with one nonreciprocal element, and a nested-ring optical modulator are presented.
", "doi": "10.7907/qzj9-rz93", "publication_date": "2022", "thesis_type": "phd", "thesis_year": "2022" }, { "id": "thesis:13857", "collection": "thesis", "collection_id": "13857", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08172020-115024354", "type": "thesis", "title": "Precision at Scale: System Design from Tiny Biosensors to Giant Arrays", "author": [ { "family_name": "Gal-Katziri", "given_name": "Matan", "orcid": "0000-0001-9100-1188", "clpid": "Gal-Katziri-Matan" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Marandi", "given_name": "Alireza", "orcid": "0000-0002-0470-0050", "clpid": "Marandi-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "In order to change the world, technological advancements must be made affordable and available for the general public to use. In other words, we must be able to scale our inventions effectively. Silicon integrated circuits are crucial components in scaling electronic systems because they are mass producible and offer a phenomenal cost-to-complexity ratio. This thesis summarizes the author\u2019s work on highly scalable sensor and array systems. It presents three high precision systems, that demonstrate how the use of highly functional radio-frequency integrated circuits enables the realization of previously unfeasible architectures.", "doi": "10.7907/t3cz-c785", "publication_date": "2021", "thesis_type": "phd", "thesis_year": "2021" }, { "id": "thesis:14080", "collection": "thesis", "collection_id": "14080", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02162021-124026838", "primary_object_url": { "basename": "Aroutin_Khachaturian Thesis Final.pdf", "content": "final", "filesize": 42602622, "license": "other", "mime_type": "application/pdf", "url": "/14080/1/Aroutin_Khachaturian Thesis Final.pdf", "version": "v7.0.0" }, "type": "thesis", "title": "Large-Scale Photonics Integration: Data Communications to Optical Beamforming", "author": [ { "family_name": "Khachaturian", "given_name": "Aroutin", "orcid": "0000-0001-8304-3302", "clpid": "Khachaturian-Aroutin" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Yang", "given_name": "Changhuei", "orcid": "0000-0001-8791-0354", "clpid": "Yang-Changhuei" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" }, { "family_name": "Vahala", "given_name": "Kerry J.", "orcid": "0000-0003-1783-1380", "clpid": "Vahala-K-J" }, { "family_name": "Scherer", "given_name": "Axel", "clpid": "Scherer-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Integrated photonics is an emerging technology that has begun to transform our way of life with the same amount of impact that integrated CMOS electronics has. Currently, photonics integration is orders of magnitude less complicated than its electronics counterparts. Nonetheless, it serves as one of the main driving forces to meet the exponentially increasing demand for high-speed and low-cost data transfer in the Information Age. It also promises to provide solutions for next-generation high-sensitivity image sensors and precision metrology and spectroscopy instruments. In this thesis, integrated photonics architectures for solid-state photonic beamforming and processing are investigated for high-resolution and high sensitivity lens-free transceiver applications. Furthermore, high-efficiency integrated electro-optical modulators aiming to meet the demand of high-density photonic integration with improved modulation efficiency, small footprint, and lower insertion loss are investigated.
\r\n\r\nTwo integrated photonic solid-state beamforming architectures incorporating two-dimensional apertures are explored. First, a novel transceiver architecture for remote sensing, coherent imaging, and ranging applications is demonstrated. It reduces system implementation complexity and offers a methodology for very-large-scale coherent transceiver beamforming applications. Next, a transmitter beamforming architecture inspired by the diffraction pattern of the slit annular ring is analyzed and demonstrated. This transceiver architecture can be used for coherent beamforming applications such as imaging and point-to-point optical communication. Finally, a coherent imager architecture for high-sensitivity three-dimensional imaging and remote-sensing applications is present. This novel architecture can suppress undesired phase fluctuations of the optical carrier signal in the illumination and reference paths, providing higher resolution and higher acquisition speed than previous implementations.
\r\n\r\nMoreover, several compact, high-speed CMOS compatible modulators that enable high-density photonic integration are explored. Ultra-compact and low insertion loss silicon-organic-hybrid modulators are designed and implemented for high-speed beamforming and high-efficiency complex signal modulation applications. Finally, a novel integrated nested-ring assisted modulator topology is analyzed and implemented for high-density and high modulation efficiency applications.
", "doi": "10.7907/xjby-xn13", "publication_date": "2021", "thesis_type": "phd", "thesis_year": "2021" }, { "id": "thesis:13957", "collection": "thesis", "collection_id": "13957", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:09182020-074010855", "type": "thesis", "title": "Active Flat Optics Wavefront Manipulation for Imaging, Ranging, and Sensing", "author": [ { "family_name": "Fatemi", "given_name": "Seyed Mohammadreza", "orcid": "0000-0001-9081-2608", "clpid": "Fatemi-Seyed-Mohammadreza" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Yang", "given_name": "Changhuei", "orcid": "0000-0001-8791-0354", "clpid": "Yang-Changhuei" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Vahala", "given_name": "Kerry J.", "orcid": "0000-0003-1783-1380", "clpid": "Vahala-K-J" }, { "family_name": "Faraon", "given_name": "Andrei", "orcid": "0000-0002-8141-391X", "clpid": "Faraon-A" }, { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The emergence and maturity of integrated photonic platforms over the past decade allowed for reliable integration of a large number of photonic components on a single substrate. This ability to process and control coherent light on a chip is a potential pathway for the realization of novel low-cost systems capable of non-conventional functionalities for optical wavefront engineering. In this thesis, integrated active flat optics architectures for generation, manipulation, and reception of optical wavefronts are investigated. In particular, the application of such systems for imaging, ranging, and sensing are studied and multiple photonic systems including a large scale transmitter, a high-sensitivity receiver, and a high-resolution transceiver are demonstrated.
\r\n\r\nFor generation of optical wavefronts, solutions for engineering a radiative optical waveform via emission by an array of nano-photonic antennas are studied and a chip-scale photonic transmitter is implemented. The transmitter forms an optical phased array with a novel architecture in a CMOS compatible silicon photonics process which not only dispenses with the limitations of previously demonstrated systems but also yields a narrower beamwidth leading to a higher resolution. Moreover, an integrated adaptive flat optical receiver architecture that collects samples of the incident light and processes it on-chip with high detection sensitivity is implemented. To detect the optical samples with a high signal to noise ratio, an optoelectronic mixer is proposed and designed that down-converts the optical signals received by each antenna to a radio frequency signal in the electronic domain, provides conversion gain, and rejects interferers. This system allows arbitrary wavefront manipulation of the received signal by adapting itself to new conditions \u2014 a capability that does not exist in conventional cameras. Using this system, we realized the first high-sensitivity optical phased array receivers with one-dimensional and two-dimensional apertures and the functionality of the chips as ultra-thin lens-less cameras were demonstrated. To achieve a high-resolution integrated photonic 3D imager with low system complexity, a double spectral sampling method is developed through a special wavefront sampling arrangement on the transmitter and receiver apertures. This transceiver architecture includes a multi-beam transmitter and a high-sensitivity receiver that can distinguish the illuminated points separately and process them simultaneously using a digital signal processor.
\r\n\r\nMoreover, novel ultra-low power architectures for generation and reception of short RF/microwave pulses are explored. Such systems have a broad range of applications including imaging and ranging. In this study, the capability of generating and receiving orthogonal Hermite pulses of various orders using a capacitor-only time-varying network is demonstrated.
", "doi": "10.7907/7e5p-9r23", "publication_date": "2021", "thesis_type": "phd", "thesis_year": "2021" }, { "id": "thesis:11755", "collection": "thesis", "collection_id": "11755", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:07252019-221240608", "primary_object_url": { "basename": "LimYuXian_FinalPhDthesis.pdf", "content": "final", "filesize": 7262509, "license": "other", "mime_type": "application/pdf", "url": "/11755/1/LimYuXian_FinalPhDthesis.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "L-Band Multi-Polarization Radar Scatterometry over Global Forests: Modelling, Analysis, and Applications", "author": [ { "family_name": "Lim", "given_name": "Yu Xian", "orcid": "0000-0002-3777-7986", "clpid": "Lim-Yu-Xian" } ], "thesis_advisor": [ { "family_name": "van Zyl", "given_name": "Jakob J.", "clpid": "van-Zyl-J-J" } ], "thesis_committee": [ { "family_name": "Elachi", "given_name": "Charles", "clpid": "Elachi-C" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Vaidyanathan", "given_name": "P. P.", "clpid": "Vaidyanathan-P-P" }, { "family_name": "van Zyl", "given_name": "Jakob J.", "clpid": "van-Zyl-J-J" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Spaceborne L-band radars have the ability to penetrate vegetation canopies over forested areas, suggesting a potential for regular and frequent global monitoring of both the vegetation state and the subcanopy soil moisture. However, L-band radar\u2019s sensitivity to both vegetation and ground also complicates the relationship between the radar observations and the ecological and geophysical parameters. Accurate yet parsimonious forward models of the radar backscatter are valuable to building an understanding of these relationships. In the first part of this thesis, a model of L-band multi-polarization radar backscatter from forests, intended for use at regional to global spatial scales, is presented. Novel developments in the model include the consideration of multiple scattering within the dense vegetation canopy, and the application of a general model of plant allometry to mitigate the need for much intensive field data for training or over-tuning towards specific sites and tree species.
\r\n\r\nAided by our model, in the remainder and majority of the thesis, a detailed analysis and interpretation of L-band backscatter over global forests is performed, using data from the Aquarius and SMAP missions. Quantitative differences in backscatter predicted by our model due to freeze/thaw states, branch orientation, and flooding are partially verified against the data, and fitted values of aboveground-biomass and microwave vegetation optical depths are comparable to independent estimates in the literature. Polarization information is used to help distinguish vegetation and ground effects on spatial and temporal variations. We show that neither vegetation nor ground effects alone can explain spatial variations within the same land cover class. For temporal variations during unfrozen periods, soil moisture is found to often be an important factor at timescales of a week to several months, although vegetation changes remain a non-negligible factor. We report the observation of significant differences in backscatter depending on beam azimuthal angle, possibly due to plant phototropism.
\r\n\r\nWe also investigated diurnal variations, which have the potential to reveal signals related to plant transpiration. SMAP data from May-July 2015 showed that globally, co-polarized backscatter was generally higher at 6PM compared to 6AM over boreal forests, which is not what one might expect based on previous studies. Based on our modelling, increased canopy extinction at 6AM is a possible cause, but this is unproven and its true underlying physical cause undetermined.
\r\n\r\nFinally, by making simplifying approximations on our forward model, we propose and explore algorithms for soil moisture retrieval under forest canopies using L-band scatterometry, with preliminary evaluations suggesting improved performance over existing algorithms.
", "doi": "10.7907/7Y4D-JD17", "publication_date": "2020", "thesis_type": "phd", "thesis_year": "2020" }, { "id": "thesis:13650", "collection": "thesis", "collection_id": "13650", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:02282020-192725947", "primary_object_url": { "basename": "Thibaud_Talon_2020_Thesis.pdf", "content": "final", "filesize": 46974399, "license": "other", "mime_type": "application/pdf", "url": "/13650/1/Thibaud_Talon_2020_Thesis.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Surface Reconstruction from Distributed Angle Measurements", "author": [ { "family_name": "Talon", "given_name": "Thibaud", "orcid": "0000-0002-8240-1101", "clpid": "Talon-Thibaud" } ], "thesis_advisor": [ { "family_name": "Pellegrino", "given_name": "Sergio", "orcid": "0000-0001-9373-3278", "clpid": "Pellegrino-S" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Meiron", "given_name": "Daniel I.", "orcid": "0000-0003-0397-3775", "clpid": "Meiron-D-I" }, { "family_name": "Chung", "given_name": "Soon-Jo", "orcid": "0000-0002-6657-3907", "clpid": "Chung-Soon-Jo" }, { "family_name": "Pellegrino", "given_name": "Sergio", "orcid": "0000-0001-9373-3278", "clpid": "Pellegrino-S" } ], "local_group": [ { "literal": "GALCIT" }, { "literal": "div_eng" } ], "abstract": "This thesis presents an innovative solution to the shape measurement of large structures for space applications. The current state-of-the-art heavily relies on optical solutions such as cameras or lasers to recover the shape of a surface. Because of the impracticality of placing a system in front of a large structure flying in space, new solutions need to be developed. The proposed solution is to embed angular sensors (such as sun sensors) directly on the surface. The sensors provide a collection of distributed measurements that form a discrete map of the angular orientation of the structure. An integration scheme can then estimate the 3D shape of the surface.
\r\n\r\nA mathematical model to perform the integration from angle measurements to the shape of a 3D surface is presented first. This model is purely geometric and serves as a basis for similar concepts. The surface is known in a reference configuration and is assumed to have deformed inextensibly to its current shape. Inextensibility conditions are enforced through a discretization of the metric tensor generating a finite number of constraints. This model parameterizes the shape of the surface using a small number of unknowns, and thus requires a small number of sensors. We study the singularities of the equations and derive necessary conditions for the problem to be well-posed. The limitations of the algorithm are highlighted. Simulations are performed on developable surfaces to analyze the performance of the method and to show the influence of the parameters used in the algorithm. Optimal schemes which lower the RMS error between the reconstructed shape and the actual one are presented.
\r\n\r\nAn experimental validation of the proposed solution and algorithm is performed on a 1.3 x 0.25 m structure with 14 embedded sun sensors. The sensors measure the two local angles of the surface from a light source placed in front of the surface. A small, lightweight and expandable design of the sensors is shown in this thesis. A calibration procedure accurately correlates the output of the sensor with a 0.5\u00b0 precision. The procedure also highlights the limitations of the design. The structure was deformed in bending and torsion with amplitudes of a few centimeters, and its shape was reconstructed to an accuracy on the order of a millimeter.
\r\n\r\nThe accuracy of the initial algorithm is found to be limited by local shape deformations caused by the mechanical response of the structure. A new algorithm, replacing the discrete inextensibility conditions with the equilibrium equations derived from a finite-element model, is shown. This new algorithm is tested on the experimental structure and the accuracy of the reconstruction is increased by a factor of 2. The RMS error is under a millimeter on average over the different applied shapes and goes as low as 0.3 mm.
\r\n\r\nTo understand how this solution can apply to large space structures, simulations are performed on a model of a large planar spacecraft. A 25 x 25 m structure representing the current concept for the Caltech Space Solar Power Project satellite is used as an example. Sensors with similar noise properties as the ones built for the experiment are placed on the spacecraft. A finite-element model combining the vibration of the spacecraft with large rigid body rotations is presented. This model is used in a Kalman filter that estimates the shape of the structure by iterative prediction from the dynamic finite-element model and correction from the angle measurements. Simulations are performed around the thruster actuation applied at the corner of the structure to follow a specific guidance scheme that is optimal for space solar power satellites. The actuation creates both vibrations of the structure with amplitudes of few centimeters and large rotations of the spacecraft. The designed Kalman filter can accurately estimate both effects and it is shown that millimeter accuracy is achievable. The relationship between the number of sensors, the reconstructed shape error, as well as potential stiffness deviations in the FE model is studied. The results provide first order estimates of the performance of this measurement system, in order to enable the design of future space missions.
", "doi": "10.7907/ZG2D-2K77", "publication_date": "2020", "thesis_type": "phd", "thesis_year": "2020" }, { "id": "thesis:11481", "collection": "thesis", "collection_id": "11481", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04222019-151834122", "type": "thesis", "title": "Metasurfaces: Beyond Diffractive and Refractive Optics", "author": [ { "family_name": "Arbabi", "given_name": "Ehsan", "orcid": "0000-0002-5328-3863", "clpid": "Arbabi-Ehsan" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Yariv", "given_name": "Amnon", "clpid": "Yariv-A" }, { "family_name": "Tai", "given_name": "Yu-Chong", "clpid": "Tai-Yu-Chong" }, { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "local_group": [ { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "Optical metasurfaces are a category of thin diffractive optical elements, fabricated using the standard micro- and nano-fabrication techniques. They provide new ways of controlling the flow of light based on various properties such as polarization, wavelength, and propagation direction. In addition, their compatibility with standard micro-fabrication techniques and compact form factor allows for the development of several novel platforms for the design and implementation of various complicated optical elements and systems. In this thesis, I first give a short overview and a brief history of the works on optical metasurfaces. Then I discuss the capabilities of metasurfaces in controlling the polarization and phase of light, and showcase their potential applications through the cases of polarimetric imaging and vectorial holography. Then, a discussion of the chromatic dispersion in optical metasurfaces is given, followed by three methods that can be utilized to design metasurfaces working at multiple discrete wavelengths. As a potential application of such metasurfaces, I present results of using them as objective lenses in two-photon microscopy. In addition, I discuss how metasurfaces enable the at-will control of chromatic dispersion in diffractive optical elements, demonstrate metasurfaces with controlled dispersion, and provide a discussion of their limitations. Integration of multiple metasurfaces into metasystems allows for implementation of complicated optical functions such as imaging and spectrometry. In this regard, I present several examples of how such metasystems can be designed, fabricated, and utilized to provide wide field of view imaging and projection, microelectromechanically tunable lenses, optical spectrometers, and retroreflectors. I conclude with an outlook on where metasurfaces can be most useful, and what limitations should be overcome before they can find wide-spread application.
", "doi": "10.7907/EQEY-KZ52", "publication_date": "2019", "thesis_type": "phd", "thesis_year": "2019" }, { "id": "thesis:11136", "collection": "thesis", "collection_id": "11136", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:07262018-030251324", "type": "thesis", "title": "Periodically Disturbed Oscillators", "author": [ { "family_name": "Hong", "given_name": "Brian Daffern", "orcid": "0000-0001-8099-0312", "clpid": "Hong-Brian-Daffern" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Vaidyanathan", "given_name": "P. P.", "clpid": "Vaidyanathan-P-P" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "By controlling the timing of events and enabling the transmission of data over long distances, oscillators can be considered to generate the \"heartbeat\" of modern electronic systems. Their utility, however, is boosted significantly by their peculiar ability to synchronize to external signals that are themselves periodic in time. Although this fascinating phenomenon has been studied by scientists since the 1600s, models for describing this behavior have seen a disconnect between the rigorous, methodical approaches taken by mathematicians and the design-oriented, physically-based analyses carried out by engineers. While the analytical power of the former is often concealed by an inundation of abstract mathematical machinery, the accuracy and generality of the latter are constrained by the empirical nature of the ensuing derivations. We hope to bridge that gap here.
\r\n\r\nIn this thesis, a general theory of electrical oscillators under the influence of a periodic injection is developed from first principles. Our approach leads to a fundamental yet intuitive understanding of the process by which oscillators lock to a periodic injection, as well as what happens when synchronization fails and the oscillator is instead injection pulled. By considering the autonomous and periodically time-varying nature that underlies all oscillators, we build a time-synchronous model that is valid for oscillators of any topology and periodic disturbances of any shape. A single first-order differential equation is shown to be capable of making accurate, quantitative predictions about a wide array of properties of periodically disturbed oscillators: the range of injection frequencies for which synchronization occurs, the phase difference between the injection and the oscillator under lock, stable vs. unstable modes of locking, the pull-in process toward lock, the dynamics of injection pulling, as well as phase noise in both free-running and injection-locked oscillators. The framework also naturally accommodates superharmonic injection-locked frequency division, subharmonic injection-locked frequency multiplication, and the general case of an arbitrary rational relationship between the injection and oscillation frequencies. A number of novel insights for improving the performance of systems that utilize injection locking are also elucidated. In particular, we explore how both the injection waveform and the oscillator's design can be modified to optimize the lock range. The resultant design techniques are employed in the implementation of a dual-moduli prescaler for frequency synthesis applications which features low power consumption, a wide operating range, and a small chip area.
\r\n\r\nFor the commonly used inductor-capacitor (LC) oscillator, we make a simple modification to our framework that takes the oscillation amplitude into account, greatly enhancing the model's accuracy for large injections. The augmented theory uniquely captures the asymmetry of the lock range as well as the distinct characteristics exhibited by different types of LC oscillators. Existing injection locking and pulling theories in the available literature are subsumed as special cases of our model. It is important to note that even though the veracity of our theoretical predictions degrades as the size of the injection grows due to our framework's linearization with respect to the disturbance, our model's validity across a broad range of practical injection strengths are borne out by simulations and measurements on a diverse collection of integrated LC, ring, and relaxation oscillators. Lastly, we also present a phasor-based analysis of LC and ring oscillators which yields a novel perspective into how the injection current interacts with the oscillator's core nonlinearity to facilitate injection locking.
", "doi": "10.7907/W0A7-4258", "publication_date": "2019", "thesis_type": "phd", "thesis_year": "2019" }, { "id": "thesis:10483", "collection": "thesis", "collection_id": "10483", "cite_using_url": "https://resolver.caltech.edu/CaltechThesis:10042017-102201104", "type": "thesis", "title": "Integrated Ultra-High-Q Nonlinear Photonic Platform for On-Chip Optoelectronic Systems", "author": [ { "family_name": "Yang", "given_name": "Kiyoul", "orcid": "0000-0002-0587-3201", "clpid": "Yang-Kiyoul" } ], "thesis_advisor": [ { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" } ], "thesis_committee": [ { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Atwater", "given_name": "Harry Albert", "clpid": "Atwater-H-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Scherer", "given_name": "Axel", "clpid": "Scherer-A" } ], "local_group": [ { "literal": "Institute for Quantum Information and Matter" }, { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "Silicon technology provided a concrete basis of the integrated microelectronics revolution, and it might usher disruptive advances in photonics again. An integrated photonic system can potentially revolutionize instrumentation, time standards, spectroscopy, and navigation. Driven by these applications, various high-Q platforms have emerged over the last decade. However, applications require to satisfy challenging combinations of ultra-high-Q (UHQ) cavity performance, monolithic integration, and nonlinear cavity designs: the monolithic integration of UHQ devices still remains elusive. In this thesis, an integrated UHQ microcavity is demonstrated for the first time. A silicon nitride waveguide is monolithically integrated with a silicon oxide cavity, and the integrated waveguide can provide nearly universal interface to other photonic devices. Significantly, this thesis discusses far beyond setting a new record for integrated Q factor: the integrated UHQ cavity provides functionality as soliton source with electronic-repetition-rates. Demonstration of low-pump-power soliton generation at 15 GHz was previously possible in only discrete devices but essentially required for integrated self-referenced comb, which can unlock new level of performance and scale in an optoelectronic system. In addition, nonlinear cavity design is another outstanding challenge towards a further development on the optoelectronic system, and will be discussed in this thesis. The dispersion-engineered platform can potentially tailor the spectral bandwidth of frequency comb, and extend the frequency comb to visible and ultraviolet band. Importantly, the design methods are directly transferable to the integrated platform.", "doi": "10.7907/Z96T0JTQ", "publication_date": "2018", "thesis_type": "phd", "thesis_year": "2018" }, { "id": "thesis:11022", "collection": "thesis", "collection_id": "11022", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06042018-194533722", "primary_object_url": { "basename": "phd-thesis_June2018.pdf", "content": "final", "filesize": 71599010, "license": "cc_by_nc", "mime_type": "application/pdf", "url": "/11022/1/phd-thesis_June2018.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Silicon Integrated Arrays: From Microwave to IR", "author": [ { "family_name": "Abiri", "given_name": "Behrooz", "orcid": "0000-0002-3317-2752", "clpid": "Abiri-Behrooz" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Integrated chips have enabled realization and mass production of complex systems in a small form factor. Through process miniaturization many novel applications in silicon photonics and electronic systems have been enabled. In this thesis I have provided several examples of innovations that are only enabled by integration. I have also demonstrated how electronics and photonics circuits can complement each other to achieve a system with superior performance.
", "doi": "10.7907/MNYK-Y158", "publication_date": "2018", "thesis_type": "phd", "thesis_year": "2018" }, { "id": "thesis:10442", "collection": "thesis", "collection_id": "10442", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:09202017-124555409", "primary_object_url": { "basename": "Horie_Yu_2018.pdf", "content": "final", "filesize": 59827475, "license": "other", "mime_type": "application/pdf", "url": "/10442/1/Horie_Yu_2018.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Controlling the Flow of Light Using High-Contrast Metastructures", "author": [ { "family_name": "Horie", "given_name": "Yu", "orcid": "0000-0001-7083-1270", "clpid": "Horie-Yu" } ], "thesis_advisor": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" } ], "thesis_committee": [ { "family_name": "Faraon", "given_name": "Andrei", "clpid": "Faraon-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" } ], "local_group": [ { "literal": "Kavli Nanoscience Institute" }, { "literal": "div_eng" } ], "abstract": "A new class of planar optical components and devices has emerged using subwavelength metastructures with a strong contrast in refractive indices. High-contrast metastructures have shown promises to manipulate optical fields in an extraordinary way and to replace conventional bulky optical elements by their low-profile analogs, typically with subwavelength-scale features. We elucidate the underlying principle, how these seemingly low-profile geometries render unique optical responses, using the coupled-mode analysis in a multimode waveguide. Moreover, strong field localization in high-index structures allows us to interpret each single element in the metastructures as a low-quality-factor resonator (or a localized scatterer), permitting us to realize designer surface that shapes phase, amplitude, and polarization of light in free space, also known as an optical metasurface. The remainder of the thesis is devoted to explore novel applications in optics using high-contrast metastructures. One of the particularly interesting applications is to use them in an optical resonator. Specifically, we demonstrate to incorporate high-contrast subwavelength grating reflectors and dielectric metasufaces in a vertical Fabry\u2013Perot cavity, and show that we can flexibly tune the resonance frequency by the subwavelength patterning. With this technique, we envision the realization of compact, on-chip spectrometers when integrating them on a photodetector array. Secondly, we investigate the use of high-contrast subwavelength gratings in visible wavelengths. We perform the optimization of their geometries and demonstrate a set of RGB color filters, down to near a micrometer in the pixel size. This platform exhibits unique performances such as high efficiency, angular insensitivity, and color tunability by the design. A novel device concept is also explored, where a high-contrast subwavelength grating reflector is integrated on a silicon platform to constitute an active resonant antenna, enabling high-speed, phase-dominant modulation by means of thermo-optic effect of silicon. We demonstrate an array of such active antennas, yielding a beam deflection capability. This justifies the robustness of our device design, enabling a large-scale integration of high-speed, phase-dominant spatial light modulators. Finally, we introduce a disorder-engineered metasurface in the context of wavefront shaping. Recently, wavefront shaping with disordered media has demonstrated optical manipulation capabilities beyond those of conventional optics, but translating this class of technology into a practical use has remained challenging due to enormous amounts of information needed to be characterized as the input-output responses. As a paradigm shift, we propose the use of disorder-engineered metasurface in wavefront shaping, where the disorder is programmatically designed and makes the system characterization-free prior to use. With this approach, we demonstrate high numerical aperture focusing in an extended volume as well as wide-field fluorescence imaging with unprecedented performances.
", "doi": "10.7907/Z94X5604", "publication_date": "2018", "thesis_type": "phd", "thesis_year": "2018" }, { "id": "thesis:10322", "collection": "thesis", "collection_id": "10322", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06082017-193807440", "type": "thesis", "title": "Electromagnetic Field Manipulation: Biosensing to Antennas", "author": [ { "family_name": "Sideris", "given_name": "Constantine", "clpid": "Sideris-Constantine" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Alon", "given_name": "Elad", "clpid": "Alon-E" }, { "family_name": "Bruno", "given_name": "Oscar P.", "clpid": "Bruno-O-P" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "We will explore how understanding and controlling electromagnetic fields can provide significant impact across a multitude of applications throughout the whole frequency spectrum from DC to daylight. Starting from the DC end of the electromagnetic spectrum, we motivate the design of a new integrated magnetic biosensing design as well as various improvements to the initial design based on spatial and temporal manipulations of the magnetic fields. Next, we look into the RF domain and develop maximal performance bounds for antennas and other electromagnetic structures. We develop rapid simulation techniques which when coupled with heuristic optimization algorithms can quickly and effectively produce new antenna structures with little to no manual intervention. We demonstrate the efficacy of these techniques in the context of on-chip antenna designs and a 3D printed coupling antenna for a dielectric waveguide communication link. We present the design of a 120GHz dual-channel 100Gbps QPSK/64QAM transceiver IC developed in a standard 28nm bulk CMOS process. Finally, we explore the higher THz regime in the context of photonic device optimization. We optimize compact photonic multiplexer devices which are fabricated in a standard foundry process and evaluate their performance against simulation results.", "doi": "10.7907/Z9RN35XW", "publication_date": "2017", "thesis_type": "phd", "thesis_year": "2017" }, { "id": "thesis:10178", "collection": "thesis", "collection_id": "10178", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05162017-205230203", "primary_object_url": { "basename": "Safaripour_Thesis.pdf", "content": "final", "filesize": 50078784, "license": "other", "mime_type": "application/pdf", "url": "/10178/19/Safaripour_Thesis.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Proximal-Field Radiation Sensors for Dynamically Controllable and Self-Correcting Integrated Radiators", "author": [ { "family_name": "Safaripour Tabbalvandani", "given_name": "Amirreza", "orcid": "0000-0001-9758-6156", "clpid": "Safaripour-Tabbalvandani-Amirreza" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Choo", "given_name": "Hyuck", "clpid": "Choo-Hyuck" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "One of the major challenges in the design of integrated radiators at mm-wave frequencies is the generation of surface waves in the dielectric substrate by the on-chip antennas. Since dielectric substrates are excellent surface waveguides with a fundamental mode with no cutoff frequency, there is always some energy trapped in them due to the surface waves and the excited substrate modes. This phenomenon is a significant cause of reduced radiation efficiency for mm-wave integrated radiators. However, in this thesis, we use this as an opportunity. We show that the excited substrate modes in the dielectric substrate of an integrated antenna contain valuable information regarding its far-field radiation properties. We introduce Proximal-Field Radiation Sensors (PFRS) as a number of small sensing antennas that are placed strategically on the same substrate as the integrated antenna and measure electromagnetic waves in its immediate proximity. These sensors extract the existing information in the substrate modes and use it to predict the far-field radiation properties of the integrated antenna in real-time based on in-situ measurements in the close proximity of the antennas, without any need to use additional test equipment and without removing the antenna from its operating environment or interfering with its operation in a wireless system. In other words, PFRS enables self-calibration, self-correction, and self-monitoring of the performance of the integrated antennas. Design intuition and a variety of data processing schemes for these sensors are discussed. Two proof-of-concept prototypes are fabricated on printed circuit board (PCB) and integrated circuit (IC) and both verify PFRS capabilities in prediction of radiation properties solely based on in-situ measurements.
\r\n\r\nDynamically controllable integrated radiators would significantly benefit from PFRS, These radiators are capable of controlling their radiation parameters such as polarization and beam steering angle through their actuators and control units. In these cases, PFRS serves as a tool for real-time monitoring of their radiation parameters, so that without direct measurement of the far-field properties through bulky equipment the required information for the control units and the actuators are provided.
\r\n\r\nDynamically controllable integrated radiators can be designed using the additional design space provided by Multi-Port Driven (MPD) radiator methodology. After a review of advantages of MPD design over the traditional single-port design, we show that a slot-based MPD radiator would have the additional advantage of reduced exclusive use area compared to the original wire-based MPD radiator, through demonstration of a 134.5-GHz integrated slot-based MPD radiator with a measured single-element EIRP of +6.0 dBm and a total radiated power of -1.3 dBm.
\r\n\r\nWe discuss how MPD methodology enables the new concept of Dynamic Polarization Control, as a method to ensure polarization matching of the transmitter antenna to the receiver antenna, regardless of the polarization and orientation of the receiver antenna in space. A DPC antenna design using the MPD methodology is described and a 105.5-GHz 2x1 integrated DPC radiator array with a maximum EIRP of +7.8 dBm and a total radiated power of 0.9 mW is presented as the first demonstration of an integrated radiator with DPC capability. This prototype can control the polarization angle across the entire tuning range of 0 to 180 degrees while maintaining axial ratios above 10 dB, and control the axial ratio from 2.4 dB (near circular) to 14 dB (linear). We also demonstrate how simultaneous two-dimensional beam steering and DPC capabilities can even match the polarization to a mobile receiver antenna through a prototype 123-GHz 2x2 integrated DPC radiator array with a maximum EIRP of +12.3 dBm, polarization angle control across the full range of 0to 180 degrees as well as tunable axial ratio down to 1.2 dB and beam steering of up to 15 degrees in both dimensions. We also use slot-based DPC antennas to fabricate a 120-GHz integrated slot-based DPC radiator array, expected to have a maximum EIRP of +15.5 dBm.
\r\n\r\nWe also introduce a new modulation scheme called Polarization Modulation (Pol-M) as a result of DPC capability, where the polarization itself is used for encoding the data. Pol-M is a spatial modulation method and is orthogonal to the existing phase and amplitude modulation schemes. Thus, it could be added on top of those schemes to enable creation of 4-D data constellations, or it can be used as the only basis for modulation to increase the stream security by misleading the undesired receivers. We discuss how DPC antenna enables Pol-M and also present PCB prototypes for Pol-M transmitter and receiver units operating at 2.4 GHz.
\r\n", "doi": "10.7907/Z9DR2SJZ", "publication_date": "2017", "thesis_type": "phd", "thesis_year": "2017" }, { "id": "thesis:10232", "collection": "thesis", "collection_id": "10232", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05312017-143935777", "primary_object_url": { "basename": "thesis_v1.pdf", "content": "final", "filesize": 191384516, "license": "other", "mime_type": "application/pdf", "url": "/10232/41/thesis_v1.pdf", "version": "v9.0.0" }, "type": "thesis", "title": "Localization and Stimulation Techniques for Implantable Medical Electronics", "author": [ { "family_name": "Monge Osorio", "given_name": "Manuel Alejandro", "orcid": "0000-0001-9799-0693", "clpid": "Monge-Osorio-Manuel-Alejandro" } ], "thesis_advisor": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Shapiro", "given_name": "Mikhail G.", "clpid": "Shapiro-M-G" } ], "thesis_committee": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Shapiro", "given_name": "Mikhail G.", "clpid": "Shapiro-M-G" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Scherer", "given_name": "Axel", "clpid": "Scherer-A" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Implantable medical devices (IMDs) are emerging as one of the keystones of tomorrow\u2019s medical technology. Although they have enabled a revolution in medicine, from research to diagnosis to treatment, most of today\u2019s devices have critical limitations. They are bulky, have low resolution, and, in some cases, are limited to basic functionality. Miniaturization of IMDs will have an enormous impact not only on the technology itself and the medical procedures they enable, but also on the lives of patients, who will be more comfortable, have greater confidence in their medical treatments, and enjoy an overall improvement in their quality of life. The path towards miniaturized bioelectronic devices requires a reevaluation of existing paradigms to reach a seamless integration of electronics and biology. Miniaturization of medical electronics then involves an exploration of advanced integrated circuit processes and novel circuit and system level architectures. In this dissertation, we provide an overview of implantable medical devices and present novel circuit and system level techniques for the miniaturization of medical electronics.
\r\n\r\nThe function of wireless miniaturized medical devices such as capsule endoscopes, biosensors, and drug delivery systems depends critically on their location inside the body. However, existing electromagnetic, acoustic, and imaging-based methods for localizing and communicating with such devices with spatial selectivity are limited by the physical properties of tissue or imaging modality performance. In the first part of this dissertation, we introduce a new approach for microscale device localization by embodying the principles of nuclear magnetic resonance in a silicon integrated circuit. By analogy to the behavior of nuclear spins, we engineer miniaturized RF transmitters that encode their location in space by shifting their output frequency in proportion to the local magnetic field. The application of external field gradients then allows each device\u2019s location to be determined precisely from the frequency of its signal. We demonstrate the core capabilities of these devices, which we call addressable transmitters operated as magnetic spins (ATOMS), in an integrated circuit smaller than 0.7 mm^3, manufactured through a standard 180 nm complementary metal-oxide-semiconductor (CMOS) process. We show that ATOMS are capable of sub-millimeter localization in vitro and in vivo. As a technology that is inherently robust to tissue properties and scalable to multiple devices, ATOMS localization provides an enabling capability for the development of microscale devices to monitor and treat disease.
\r\n\r\nIn neuroprosthetics, retinal prostheses aim to restore vision in patients suffering from advanced stages of retinal degeneration (e.g., retinitis pigmentosa) by bypassing the damaged photoreceptors and directly stimulating the remaining healthy neurons. In the second part of this dissertation, we describe a fully intraocular self-calibrating epiretinal prosthesis that reduces area and power consumption, and increases the functionality and resolution of traditional implementations. We introduce a novel novel digital calibration technique that matches the biphasic stimulation currents of each channel independently while sharing the calibration circuitry among every 4 channels. The system-on-chip presents dual-band telemetry for power and data with on-chip rectifier and clock recovery. These techniques reduce the number of off-chip components and achieve a power conversion efficiency >80% and supporting data rates up to 20 Mb/s. The system occupies an area of 4.5 x 3.1 mm2 and is implemented in 65 nm CMOS . It features 512 independent channels with a pixel size of 0.0169 mm2 and arbitrary waveform generation per channel. The chip is integrated with flexible MEMS origami coils and parylene substrate to provide a fully intraocular implant.
", "doi": "10.7907/Z9P55KJ7", "publication_date": "2017", "thesis_type": "phd", "thesis_year": "2017" }, { "id": "thesis:10284", "collection": "thesis", "collection_id": "10284", "cite_using_url": "https://resolver.caltech.edu/CaltechThesis:06052017-131214880", "primary_object_url": { "basename": "Hong_Brian_Eng2017.pdf", "content": "final", "filesize": 5037212, "license": "other", "mime_type": "application/pdf", "url": "/10284/1/Hong_Brian_Eng2017.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Mathematical Modeling of Electronic Systems: From Oscillators to Multipliers", "author": [ { "family_name": "Hong", "given_name": "Brian Daffern", "orcid": "0000-0001-8099-0312", "clpid": "Hong-Brian-Daffern" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Hassibi", "given_name": "Babak", "clpid": "Hassibi-B" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The ubiquity of electronics in modern technology is undeniable. Although it is not feasible to design or analyze circuits in an exhaustively detailed fashion, it is still imperative that circuit design engineers understand the pertinent physical tradeoffs and are able to think at the appropriate level of mathematical abstraction. This thesis presents several mathematical modeling techniques of common electronic systems.
\r\n\r\nFirst, we derive, ab initio, a general analytical model for the behavior of electrical oscillators under injection without making any assumptions about the type of oscillator or the size or shape of the injection. This model provides novel insights into the phenomena of injection locking and pulling while subsuming existing theories found in the literature. Next, we focus on the familiar scenario of an inductor-capacitor (LC) oscillator locked to a sinusoidal signal. An exact analysis of this circuit is carried out for an arbitrary injection strength and frequency, a task which has not been executed to fruition in the existing literature. This analysis intuitively illuminates the fundamental physics underlying the synchronization of electrical harmonic oscillators, and it generalizes the notion of the lock range for such oscillators into separate necessary and sufficient conditions. We then turn to the classical estimate of the bandwidth of a linear time-invariant (LTI) system via the sum of its zero-value time constants (ZVTs), and we show that this sum can actually be used to tightly bound the bandwidth\u2014both from above and from below\u2014in addition to simply estimating it. Finally, we look at a natural generalization of the Gilbert cell topology: an analog multiplier for an arbitrary number of inputs; we then analyze its large- and small-signal characteristics as well as its frequency response.
\r\n\r\nThroughout, we will demonstrate how infusing physical intuition with mathematical rigor whilst seeking a balance between detailed analysis and abstract modularity results in models that are conceptually insightful, sufficiently accurate, and computationally feasible.
", "doi": "10.7907/Z9RB72NG", "publication_date": "2017", "thesis_type": "engd", "thesis_year": "2017" }, { "id": "thesis:9234", "collection": "thesis", "collection_id": "9234", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10212015-150203289", "primary_object_url": { "basename": "Thesis.pdf", "content": "final", "filesize": 109730024, "license": "other", "mime_type": "application/pdf", "url": "/9234/1/Thesis.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Holistic Design In High-Speed Optical Interconnects", "author": [ { "family_name": "Saeedi", "given_name": "Saman", "clpid": "Saeedi-Saman" } ], "thesis_advisor": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" } ], "thesis_committee": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Choo", "given_name": "Hyuck", "clpid": "Choo-Hyuck" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Integrated circuit scaling has enabled a huge growth in processing capability, which necessitates a corresponding increase in inter-chip communication bandwidth. As bandwidth requirements for chip-to-chip interconnection scale, deficiencies of electrical channels become more apparent. Optical links present a viable alternative due to their low frequency-dependent loss and higher bandwidth density in the form of wavelength division multiplexing. As integrated photonics and bonding technologies are maturing, commercialization of hybrid-integrated optical links are becoming a reality. Increasing silicon integration leads to better performance in optical links but necessitates a corresponding co-design strategy in both electronics and photonics. In this light, holistic design of high-speed optical links with an in-depth understanding of photonics and state-of-the-art electronics brings their performance to unprecedented levels. This thesis presents developments in high-speed optical links by co-designing and co-integrating the primary elements of an optical link: receiver, transmitter, and clocking.
\r\n\r\nIn the first part of this thesis a 3D-integrated CMOS/Silicon-photonic receiver will be presented. The electronic chip features a novel design that employs a low-bandwidth TIA front-end, double-sampling and equalization through dynamic offset modulation. Measured results show -14.9dBm of sensitivity and energy efficiency of 170fJ/b at 25Gb/s. The same receiver front-end is also used to implement source-synchronous 4-channel WDM-based parallel optical receiver. Quadrature ILO-based clocking is employed for synchronization and a novel frequency-tracking method that exploits the dynamics of IL in a quadrature ring oscillator to increase the effective locking range. An adaptive body-biasing circuit is designed to maintain the per-bit-energy consumption constant across wide data-rates. The prototype measurements indicate a record-low power consumption of 153fJ/b at 32Gb/s. The receiver sensitivity is measured to be -8.8dBm at 32Gb/s.
\r\n\r\nNext, on the optical transmitter side, three new techniques will be presented. First one is a differential ring modulator that breaks the optical bandwidth/quality factor trade-off known to limit the speed of high-Q ring modulators. This structure maintains a constant energy in the ring to avoid pattern-dependent power droop. As a first proof of concept, a prototype has been fabricated and measured up to 10Gb/s. The second technique is thermal stabilization of micro-ring resonator modulators through direct measurement of temperature using a monolithic PTAT temperature sensor. The measured temperature is used in a feedback loop to adjust the thermal tuner of the ring. A prototype is fabricated and a closed-loop feedback system is demonstrated to operate at 20Gb/s in the presence of temperature fluctuations. The third technique is a switched-capacitor based pre-emphasis technique designed to extend the inherently low bandwidth of carrier injection micro-ring modulators. A measured prototype of the optical transmitter achieves energy efficiency of 342fJ/bit at 10Gb/s and the wavelength stabilization circuit based on the monolithic PTAT sensor consumes 0.29mW.
\r\n\r\nLastly, a first-order frequency synthesizer that is suitable for high-speed on-chip clock generation will be discussed. The proposed design features an architecture combining an LC quadrature VCO, two sample-and-holds, a PI, digital coarse-tuning, and rotational frequency detection for fine-tuning. In addition to an electrical reference clock, as an extra feature, the prototype chip is capable of receiving a low jitter optical reference clock generated by a high-repetition-rate mode-locked laser. The output clock at 8GHz has an integrated RMS jitter of 490fs, peak-to-peak periodic jitter of 2.06ps, and total RMS jitter of 680fs. The reference spurs are measured to be \u201364.3dB below the carrier frequency. At 8GHz the system consumes 2.49mW from a 1V supply.
", "doi": "10.7907/Z9K935HH", "publication_date": "2016", "thesis_type": "phd", "thesis_year": "2016" }, { "id": "thesis:8944", "collection": "thesis", "collection_id": "8944", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05302015-005943888", "primary_object_url": { "basename": "Pai_Alex_2015_06_12_thesis.pdf", "content": "final", "filesize": 35439405, "license": "other", "mime_type": "application/pdf", "url": "/8944/1/Pai_Alex_2015_06_12_thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Sensing and Actuation from Biology to Electronics", "author": [ { "family_name": "Pai", "given_name": "Alex Hao-Yu", "clpid": "Pai-Alex-Hao-Yu" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Choo", "given_name": "Hyuck", "clpid": "Choo-Hyuck" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "We introduce an in vitro diagnostic magnetic biosensing platform for immunoassay and nucleic acid detection. The platform has key characteristics for a point-of-use (POU) diagnostic: portability, low-power consumption, low cost, and multiplexing capability. As a demonstration of capabilities, we use this platform for the room temperature, amplification-free detection of a 31 bp DNA oligomer and interferon-gamma (a protein relevant for tuberculosis diagnosis). Reliable assay measurements down to 100 pM for the DNA and 1 pM for the protein are demonstrated. We introduce a novel \"magnetic freezing\" technique for baseline measurement elimination and to enable spatial multiplexing. We have created a general protocol for adapting integrated circuit (IC) sensors to any of hundreds of commercially available immunoassay kits and custom designed DNA sequences.
\r\n\r\nWe also introduce a method for immunotherapy treatment of malignant gliomas. We utilize leukocytes internalized with immunostimulatory nanoparticle-oligonucleotide conjugates to localize and retain immune cells near the tumor site. As a proof-of-principle, we develop a novel cell imaging and incubation chamber for in vitro magnetic motility experiments. We use the apparatus to demonstrate the controlled movement of magnetically loaded THP-1 leukocytes.
\r\n\r\nFinally, we introduce an IC transmitter and power ampli er (PA) that utilizes electronic digital infrastructure, sensors, and actuators to self-heal and adapt to process, dynamic, and environmental variation. Traditional IC design has achieved incredible degrees of reliability by ensuring that billions of transistors on a single IC die are all simultaneously functional. Reliability becomes increasingly difficult as the size of a transistor shrinks. Self-healing can mitigate these variations.
", "doi": "10.7907/Z9NC5Z5M", "publication_date": "2015", "thesis_type": "phd", "thesis_year": "2015" }, { "id": "thesis:8717", "collection": "thesis", "collection_id": "8717", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10282014-113257585", "primary_object_url": { "basename": "KaushikThesis.pdf", "content": "final", "filesize": 22700825, "license": "other", "mime_type": "application/pdf", "url": "/8717/1/KaushikThesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Self-Healing Techniques for RF and mm-Wave Transmitters and Receivers", "author": [ { "family_name": "Dasgupta", "given_name": "Kaushik", "clpid": "Dasgupta-Kaushik" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Choo", "given_name": "Hyuck", "clpid": "Choo-Hyuck" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "With continuing advances in CMOS technology, feature sizes of modern Silicon chip-sets have gone down drastically over the past decade. In addition to desktops and laptop processors, a vast majority of these chips are also being deployed in mobile communication devices like smart-phones and tablets, where multiple radio-frequency integrated circuits (RFICs) must be integrated into one device to cater to a wide variety of applications such as Wi-Fi, Bluetooth, NFC, wireless charging, etc. While a small feature size enables higher integration levels leading to billions of transistors co-existing on a single chip, it also makes these Silicon ICs more susceptible to variations. A part of these variations can be attributed to the manufacturing process itself, particularly due to the stringent dimensional tolerances associated with the lithographic steps in modern processes. Additionally, RF or millimeter-wave communication chip-sets are subject to another type of variation caused by dynamic changes in the operating environment. Another bottleneck in the development of high performance RF/mm-wave Silicon ICs is the lack of accurate analog/high-frequency models in nanometer CMOS processes. This can be primarily attributed to the fact that most cutting edge processes are geared towards digital system implementation and as such there is little model-to-hardware correlation at RF frequencies.
\r\n\r\nAll these issues have significantly degraded yield of high performance mm-wave and RF CMOS systems which often require multiple trial-and-error based Silicon validations, thereby incurring additional production costs. This dissertation proposes a low overhead technique which attempts to counter the detrimental effects of these variations, thereby improving both performance and yield of chips post fabrication in a systematic way. The key idea behind this approach is to dynamically sense the performance of the system, identify when a problem has occurred, and then actuate it back to its desired performance level through an intelligent on-chip optimization algorithm. We term this technique as self-healing drawing inspiration from nature's own way of healing the body against adverse environmental effects. To effectively demonstrate the efficacy of self-healing in CMOS systems, several representative examples are designed, fabricated, and measured against a variety of operating conditions.
\r\n\r\nWe demonstrate a high-power mm-wave segmented power mixer array based transmitter architecture that is capable of generating high-speed and non-constant envelope modulations at higher efficiencies compared to existing conventional designs. We then incorporate several sensors and actuators into the design and demonstrate closed-loop healing against a wide variety of non-ideal operating conditions. We also demonstrate fully-integrated self-healing in the context of another mm-wave power amplifier, where measurements were performed across several chips, showing significant improvements in performance as well as reduced variability in the presence of process variations and load impedance mismatch, as well as catastrophic transistor failure. Finally, on the receiver side, a closed-loop self-healing phase synthesis scheme is demonstrated in conjunction with a wide-band voltage controlled oscillator to generate phase shifter local oscillator (LO) signals for a phased array receiver. The system is shown to heal against non-idealities in the LO signal generation and distribution, significantly reducing phase errors across a wide range of frequencies.
", "doi": "10.7907/Z9HQ3WTR", "publication_date": "2015", "thesis_type": "phd", "thesis_year": "2015" }, { "id": "thesis:8719", "collection": "thesis", "collection_id": "8719", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:11062014-090236636", "type": "thesis", "title": "Injection Locked Clocking and Transmitter Equalization Techniques for Chip to Chip Interconnects", "author": [ { "family_name": "Raj", "given_name": "Mayank", "clpid": "Raj-Mayank" } ], "thesis_advisor": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" } ], "thesis_committee": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Choo", "given_name": "Hyuck", "clpid": "Choo-Hyuck" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Semiconductor technology scaling has enabled drastic growth in the computational capacity of integrated circuits (ICs). This constant growth drives an increasing demand for high bandwidth communication between ICs. Electrical channel bandwidth has not been able to keep up with this demand, making I/O link design more challenging. Interconnects which employ optical channels have negligible frequency dependent loss and provide a potential solution to this I/O bandwidth problem. Apart from the type of channel, efficient high-speed communication also relies on generation and distribution of multi-phase, high-speed, and high-quality clock signals. In the multi-gigahertz frequency range, conventional clocking techniques have encountered several design challenges in terms of power consumption, skew and jitter. Injection-locking is a promising technique to address these design challenges for gigahertz clocking. However, its small locking range has been a major contributor in preventing its ubiquitous acceptance.
\r\n \r\nIn the first part of this dissertation we describe a wideband injection locking scheme in an LC oscillator. Phase locked loop (PLL) and injection locking elements are combined symbiotically to achieve wide locking range while retaining the simplicity of the latter. This method does not require a phase frequency detector or a loop filter to achieve phase lock. A mathematical analysis of the system is presented and the expression for new locking range is derived. A locking range of 13.4 GHz\u201317.2 GHz (25%) and an average jitter tracking bandwidth of up to 400 MHz are measured in a high-Q LC oscillator. This architecture is used to generate quadrature phases from a single clock without any frequency division. It also provides high frequency jitter filtering while retaining the low frequency correlated jitter essential for forwarded clock receivers.
\r\n\r\nTo improve the locking range of an injection locked ring oscillator; QLL (Quadrature locked loop) is introduced. The inherent dynamics of injection locked quadrature ring oscillator are used to improve its locking range from 5% (7-7.4GHz) to 90% (4-11GHz). The QLL is used to generate accurate clock phases for a four channel optical receiver using a forwarded clock at quarter-rate. The QLL drives an injection locked oscillator (ILO) at each channel without any repeaters for local quadrature clock generation. Each local ILO has deskew capability for phase alignment. The optical-receiver uses the inherent frequency to voltage conversion provided by the QLL to dynamically body bias its devices. A wide locking range of the QLL helps to achieve a reliable data-rate of 16-32Gb/s and adaptive body biasing aids in maintaining an ultra-low power consumption of 153pJ/bit.
\r\n \r\nFrom the optical receiver we move on to discussing a non-linear equalization technique for a vertical-cavity surface-emitting laser (VCSEL) based optical transmitter, to enable low-power, high-speed optical transmission. A non-linear time domain optical model of the VCSEL is built and evaluated for accuracy. The modelling shows that, while conventional FIR-based pre-emphasis works well for LTI electrical channels, it is not optimum for the non-linear optical frequency response of the VCSEL. Based on the simulations of the model an optimum equalization methodology is derived. The equalization technique is used to achieve a data-rate of 20Gb/s with power efficiency of 0.77pJ/bit.
\r\n", "doi": "10.7907/Z90P0WZD", "publication_date": "2015", "thesis_type": "phd", "thesis_year": "2015" }, { "id": "thesis:8898", "collection": "thesis", "collection_id": "8898", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05282015-141343540", "primary_object_url": { "basename": "saFN999I9qeezyfjOAIBOSbqqbgW0lXJe8VCTAf7R624ttavA87cha2LoU7i0CUv", "content": "final", "filesize": 72440132, "license": "other", "mime_type": "application/pdf", "url": "/8898/1/saFN999I9qeezyfjOAIBOSbqqbgW0lXJe8VCTAf7R624ttavA87cha2LoU7i0CUv", "version": "v4.0.0" }, "type": "thesis", "title": "Instrumentation for Kinetic-Inductance-Detector-Based Submillimeter Radio Astronomy", "author": [ { "family_name": "Duan", "given_name": "Ran", "clpid": "Duan-Ran" } ], "thesis_advisor": [ { "family_name": "Golwala", "given_name": "Sunil", "clpid": "Golwala-S-R" } ], "thesis_committee": [ { "family_name": "Golwala", "given_name": "Sunil", "clpid": "Golwala-S-R" }, { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "Astronomy Department" }, { "literal": "div_eng" } ], "abstract": "A substantial amount of important scientific information is contained within astronomical data at the submillimeter and far-infrared (FIR) wavelengths, including information regarding dusty galaxies, galaxy clusters, and star-forming regions; however, these wavelengths are among the least-explored\r\nfields in astronomy because of the technological difficulties involved in such research. Over the past 20 years, considerable efforts have been devoted to developing submillimeter- and millimeter-wavelength astronomical instruments and telescopes.
\r\n\r\nThe number of detectors is an important property of such instruments and is the subject of the current study. Future telescopes will require as many as hundreds of thousands of detectors to meet the necessary requirements in terms of the field of view, scan speed, and resolution. A large pixel count is one benefit of the development of multiplexable detectors that use kinetic inductance detector (KID) technology.
\r\n\r\nThis dissertation presents the development of a KID-based instrument including a portion of the millimeter-wave bandpass filters and all aspects of the readout electronics, which together enabled one of the largest detector counts achieved to date in submillimeter-/millimeter-wavelength imaging arrays: a total of 2304 detectors. The work presented in this dissertation has been implemented in the MUltiwavelength Submillimeter Inductance Camera (MUSIC), a new instrument for the Caltech Submillimeter Observatory (CSO).
", "doi": "10.7907/Z90P0WXZ", "publication_date": "2015", "thesis_type": "phd", "thesis_year": "2015" }, { "id": "thesis:8737", "collection": "thesis", "collection_id": "8737", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:12052014-154140797", "primary_object_url": { "basename": "AlborzThesisFinal.pdf", "content": "final", "filesize": 11354462, "license": "other", "mime_type": "application/pdf", "url": "/8737/1/AlborzThesisFinal.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Synthetic Biology Tools for Targeted Incorporation of Non-Canonical Amino Acids into Cellular Proteins", "author": [ { "family_name": "Mahdavi", "given_name": "Alborz", "orcid": "0000-0002-8790-8112", "clpid": "Mahdavi-Alborz" } ], "thesis_advisor": [ { "family_name": "Tirrell", "given_name": "David A.", "orcid": "0000-0003-3175-4596", "clpid": "Tirrell-D-A" } ], "thesis_committee": [ { "family_name": "Tirrell", "given_name": "David A.", "orcid": "0000-0003-3175-4596", "clpid": "Tirrell-D-A" }, { "family_name": "Mazmanian", "given_name": "Sarkis K.", "orcid": "0000-0003-2713-1513", "clpid": "Mazmanian-S-K" }, { "family_name": "Elowitz", "given_name": "Michael B.", "orcid": "0000-0002-1221-0967", "clpid": "Elowitz-M-B" }, { "family_name": "Arnold", "given_name": "Frances Hamilton", "orcid": "0000-0002-4027-364X", "clpid": "Arnold-F-H" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Proteins mediate many essential functions in cells, and methods to profile cellular proteins are of great interest for biological discovery. Whereas all of the cells in an organism share the same genome, the landscape of proteins (the proteome) varies between different cell types and over the lifetime of the organism. Rapid progress in mass spectrometers is enabling the detailed analysis of cellular proteomes. Whereas better instruments increase coverage, throughput, and measurement precision, new chemical reporters, metabolic tags, and synthetic biology techniques are required to enhance the specificity and spatiotemporal resolution of protein labeling and detection. This work introduces methods for cell-selective proteome analysis through the incorporation of non-canonical amino acids into newly synthesized proteins.
\r\n \r\nChapter I provides an overview of current technologies for translational profiling and proteomic analysis in cells. Strategies for the residue-specific incorporation of non-canonical amino acids and bioorthogonal non-canonical amino acid tagging are discussed. Chapter II introduces a new approach for the identification of secreted bacterial proteins from infected host cells using non-canonical amino acid labeling. This work demonstrates an application of cell-selective proteome labeling. Selectivity is achieved through controlled expression of a mutant aminoacyl tRNA synthetase (aaRS) enzyme that enables the metabolic incorporation of a non-canonical amino acid.
\r\n \r\nIdeally, the activity of multiple genes should be used to genetically control the extent of proteome labeling in cells. This is useful because many cell states are characterized by the activity of multiple genes and identified based on the expression of several proteins. Therefore chapter III introduces a novel approach to control proteome labeling as a function of multiple promoters using a genetically encoded AND gate based on a bisected methionyl-tRNA synthetase, a class I aaRS. Cellular protein labeling occurs only upon activation of two different promoters that drive expression of the N- and C-terminal fragments of this bisected aaRS. The utility of this tool is demonstrated by the selective labeling of proteins in subpopulations of bacterial cells in a laminar-flow microfluidic channel.
\r\n \r\nChapter IV extends the cell-selective incorporation of non-canonical amino acids from bacterial systems to mammalian cells by introducing a mutant mammalian methionyl-tRNA synthetase for cell-targeted proteome labeling. This enzyme is genetically encoded and can be conditionally activated for time-resolved and cell-targeted proteome analysis in a variety of different mammalian cell types. Chapter V uses this enzyme for lineage-specific proteomic analysis of mouse embryonic stem cells during differentiation to cardiac and mesoderm lineages. This approach for lineage-specific protein labeling enables the unbiased and comprehensive analysis of proteomic changes that occur during stem cell differentiation and cell-fate commitment.
\r\n \r\nAppendices A-G provide brief summaries of publications and research efforts during my PhD that are not directly related to this thesis. These publications are the result of a number of collaborations that I have been fortunate to be involved with during my graduate research.
\r\n\r\nThe technologies and methods introduced in this thesis provide versatile tools for the comprehensive and unbiased detection and identification of newly synthesized proteins in complex multicellular systems. Time-resolved, genetically encoded, and spatially defined non-canonical amino acid incorporation enables the identification of proteins involved in cell-cell interactions and the proteins made during specific cell states.
\r\n", "doi": "10.7907/Z9W66HS4", "publication_date": "2015", "thesis_type": "phd", "thesis_year": "2015" }, { "id": "thesis:8654", "collection": "thesis", "collection_id": "8654", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:09082014-135331211", "type": "thesis", "title": "Macroscopically Dissipative Systems with Underlying Microscopic Dynamics : Properties and Limits of Measurement", "author": [ { "family_name": "Asimakopoulos", "given_name": "Aristotelis", "clpid": "Asimakopoulos-Aristotelis" } ], "thesis_advisor": [ { "family_name": "Doyle", "given_name": "John Comstock", "orcid": "0000-0002-1828-2486", "clpid": "Doyle-J-C" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Phillips", "given_name": "Robert B.", "orcid": "0000-0003-3082-2809", "clpid": "Phillips-R" }, { "family_name": "Chandy", "given_name": "K. Mani", "orcid": "0000-0001-9190-1290", "clpid": "Chandy-K-M" }, { "family_name": "Doyle", "given_name": "John Comstock", "orcid": "0000-0002-1828-2486", "clpid": "Doyle-J-C" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "While some of the deepest results in nature are those that give explicit bounds between important physical quantities, some of the most intriguing and celebrated of such bounds come from fields where there is still a great deal of disagreement and confusion regarding even the most fundamental aspects of the theories. For example, in quantum mechanics, there is still no complete consensus as to whether the limitations associated with Heisenberg's Uncertainty Principle derive from an inherent randomness in physics, or rather from limitations in the measurement process itself, resulting from phenomena like back action. Likewise, the second law of thermodynamics makes a statement regarding the increase in entropy of closed systems, yet the theory itself has neither a universally-accepted definition of equilibrium, nor an adequate explanation of how a system with underlying microscopically Hamiltonian dynamics (reversible) settles into a fixed distribution.
\r\n\r\nMotivated by these physical theories, and perhaps their inconsistencies, in this thesis we use dynamical systems theory to investigate how the very simplest of systems, even with no physical constraints, are characterized by bounds that give limits to the ability to make measurements on them. Using an existing interpretation, we start by examining how dissipative systems can be viewed as high-dimensional lossless systems, and how taking this view necessarily implies the existence of a noise process that results from the uncertainty in the initial system state. This fluctuation-dissipation result plays a central role in a measurement model that we examine, in particular describing how noise is inevitably injected into a system during a measurement, noise that can be viewed as originating either from the randomness of the many degrees of freedom of the measurement device, or of the environment. This noise constitutes one component of measurement back action, and ultimately imposes limits on measurement uncertainty. Depending on the assumptions we make about active devices, and their limitations, this back action can be offset to varying degrees via control. It turns out that using active devices to reduce measurement back action leads to estimation problems that have non-zero uncertainty lower bounds, the most interesting of which arise when the observed system is lossless. One such lower bound, a main contribution of this work, can be viewed as a classical version of a Heisenberg uncertainty relation between the system's position and momentum. We finally also revisit the murky question of how macroscopic dissipation appears from lossless dynamics, and propose alternative approaches for framing the question using existing systematic methods of model reduction.
", "doi": "10.7907/Z9V40S4N", "publication_date": "2015", "thesis_type": "phd", "thesis_year": "2015" }, { "id": "thesis:7988", "collection": "thesis", "collection_id": "7988", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10102013-145125571", "primary_object_url": { "basename": "BowersThesis_Oct9_2013.pdf", "content": "final", "filesize": 11580240, "license": "other", "mime_type": "application/pdf", "url": "/7988/1/BowersThesis_Oct9_2013.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Dynamically Controllable Integrated Radiation and Self-Correcting Power Generation in mm-Wave Circuits and Systems", "author": [ { "family_name": "Bowers", "given_name": "Steven Michael", "clpid": "Bowers-Steven-Michael" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Choo", "given_name": "Hyuck", "clpid": "Choo-Hyuck" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "This thesis presents novel design methodologies for integrated radiators and power generation at mm-wave frequencies that are enabled by the continued integration of various electronic and electromagnetic (EM) structures onto the same substrate. Beginning with the observation that transistors and their connections to EM radiating structures on an integrated substrate are essentially free, the concept of multi-port driven (MPD) radiators is introduced, which opens a vast design space that has been generally ignored due to the cost structure associated with discrete components that favors fewer transistors connected to antennas through a single port.
\r\n\r\nFrom Maxwell's equations, a new antenna architecture, the radial MPD antennas based on the concept of MPD radiators, is analyzed to gain intuition as to the important design parameters that explain the wide-band nature of the antenna itself. The radiator is then designed and implemented at 160 GHz in a 0.13 um SiGe BiCMOS process, and the single element design has a measured effective isotropic radiated power (EIRP) of +4.6 dBm with a total radiated power of 0.63 mW.
\r\n\r\nNext, the radial MPD radiator is adapted to enable dynamic polarization control (DPC). A DPC antenna is capable of controlling its radiated polarization dynamically, and entirely electronically, with no mechanical reconfiguration required. This can be done by having multiple antennas with different polarizations, or within a single antenna that has multiple drive points, as in the case of the MPD radiator with DPC. This radiator changes its polarization by adjusting the relative phase and amplitude of its multiple ports to produce polarizations with any polarization angle, and a wide range of axial ratios. A 2x1 MPD radiator array with DPC at 105 GHz is presented whose measurements show control of the polarization angle throughout the entire 0 degree through 180 degree range while in the linear polarization mode and maintaining axial ratios above 10 dB in all cases. Control of the axial ratio is also demonstrated with a measured range from 2.4 dB through 14 dB, while maintaining a fixed polarization angle. The radiator itself has a measured maximum EIRP of +7.8 dBm, with a total radiated power of 0.9 mW, and is capable of beam steering.
\r\n \r\nMPD radiators were also applied in the domain of integrated silicon photonics. For these designs, the driver transistor circuitry was replaced with silicon optical waveguides and photodiodes to produce a 350 GHz signal. Three of these optical MPD radiator designs have been implemented as 2x2 arrays at 350 GHz. The first is a beam forming array that has a simulated gain of 12.1 dBi with a simulated EIRP of -2 dBm. The second has the same simulated performance, but includes optical phase modulators that enable two-dimensional beam steering. Finally, a third design incorporates multi-antenna DPC by combining the outputs of both left and right handed circularly polarized MPD antennas to produce a linear polarization with controllable polarization angle, and has a simulated gain of 11.9 dBi and EIRP of -3 dBm. In simulation, it can tune the polarization from 0 degrees through 180 degrees while maintaining a radiated power that has a 0.35 dB maximum deviation from the mean.
\r\n\r\nThe reliability of mm-wave radiators and power amplifiers was also investigated, and two self-healing systems have been proposed. Self-healing is a global feedback method where integrated sensors detect the performance of the circuit after fabrication and report that data to a digital control algorithm. The algorithm then is capable of setting actuators that can control the performance of the mm-wave circuit and counteract any performance degradation that is observed by the sensors. The first system is for a MPD radiator array with a partially integrated self-healing system. The self-healing MPD radiator senses substrate modes through substrate mode pickup sensors and infers the far-field radiated pattern from those sensors. DC current sensors are also included to determine the DC power consumption of the system. Actuators are implemented in the form of phase and amplitude control of the multiple drive points.
\r\n\r\nThe second self-healing system is a fully integrated self-healing power amplifier (PA) at 28 GHz. This system measures the output power, gain and efficiency of the PA using radio frequency (RF) power sensors, DC current sensors and junction temperature sensors. The digital block is synthesized from VHDL code on-chip and it can actuate the output power combining matching network using tunable transmission line stubs, as well as the DC operating point of the amplifying transistors through bias control. Measurements of 20 chips confirm self-healing for two different algorithms for process variation and transistor mismatch, while measurements from 10 chips show healing for load impedance mismatch, and linearity healing. Laser induced partial and total transistor failure show the benefit of self-healing in the case of catastrophic failure, with improvements of up to 3.9 dB over the default case. An exemplary yield specification shows self-healing improving the yield from 0% up through 80%.
", "doi": "10.7907/Z9MP518K", "publication_date": "2014", "thesis_type": "phd", "thesis_year": "2014" }, { "id": "thesis:7762", "collection": "thesis", "collection_id": "7762", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05282013-164038057", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 19208500, "license": "other", "mime_type": "application/pdf", "url": "/7762/1/thesis.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Electrical and Optical Interconnects for High-Performance Computing", "author": [ { "family_name": "Honarvar Nazari", "given_name": "Meisam", "clpid": "Honarvar-Nazari-Meisam" } ], "thesis_advisor": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" } ], "thesis_committee": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Choo", "given_name": "Hyuck", "clpid": "Choo-Hyuck" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Technology scaling has enabled drastic growth in the computational and storage capacity of integrated circuits (ICs). This constant growth drives an increasing demand for high-bandwidth communication between and within ICs. In this dissertation we focus on low-power solutions that address this demand. We divide communication links into three subcategories depending on the communication distance. Each category has a different set of challenges and requirements and is affected by CMOS technology scaling in a different manner. We start with short-range chip-to-chip links for board-level communication. Next we will discuss board-to-board links, which demand a longer communication range. Finally on-chip links with communication ranges of a few millimeters are discussed.
\r\n\r\nElectrical signaling is a natural choice for chip-to-chip communication due to efficient integration and low cost. IO data rates have increased to the point where electrical signaling is now limited by the channel bandwidth. In order to achieve multi-Gb/s data rates, complex designs that equalize the channel are necessary. In addition, a high level of parallelism is central to sustaining bandwidth growth. Decision feedback equalization (DFE) is one of the most commonly employed techniques to overcome the limited bandwidth problem of the electrical channels. A linear and low-power summer is the central block of a DFE. Conventional approaches employ current-mode techniques to implement the summer, which require high power consumption. In order to achieve low-power operation we propose performing the summation in the charge domain. This approach enables a low-power and compact realization of the DFE as well as crosstalk cancellation. A prototype receiver was fabricated in 45nm SOI CMOS to validate the functionality of the proposed technique and was tested over channels with different levels of loss and coupling. Measurement results show that the receiver can equalize channels with maximum 21dB loss while consuming about 7.5mW from a 1.2V supply. We also introduce a compact, low-power transmitter employing passive equalization. The efficacy of the proposed technique is demonstrated through implementation of a prototype in 65nm CMOS. The design achieves up to 20Gb/s data rate while consuming less than 10mW.
\r\n \r\nAn alternative to electrical signaling is to employ optical signaling for chip-to-chip interconnections, which offers low channel loss and cross-talk while providing high communication bandwidth. In this work we demonstrate the possibility of building compact and low-power optical receivers. A novel RC front-end is proposed that combines dynamic offset modulation and double-sampling techniques to eliminate the need for a short time constant at the input of the receiver. Unlike conventional designs, this receiver does not require a high-gain stage that runs at the data rate, making it suitable for low-power implementations. In addition, it allows time-division multiplexing to support very high data rates. A prototype was implemented in 65nm CMOS and achieved up to 24Gb/s with less than 0.4pJ/b power efficiency per channel. As the proposed design mainly employs digital blocks, it benefits greatly from technology scaling in terms of power and area saving.
\r\n\r\nAs the technology scales, the number of transistors on the chip grows. This necessitates a corresponding increase in the bandwidth of the on-chip wires. In this dissertation, we take a close look at wire scaling and investigate its effect on wire performance metrics. We explore a novel on-chip communication link based on a double-sampling architecture and dynamic offset modulation technique that enables low power consumption and high data rates while achieving high bandwidth density in 28nm CMOS technology. The functionality of the link is demonstrated using different length minimum-pitch on-chip wires. Measurement results show that the link achieves up to 20Gb/s of data rate (12.5Gb/s/$\\mu$m) with better than 136fJ/b of power efficiency.
", "doi": "10.7907/TSX2-EE48", "publication_date": "2013", "thesis_type": "phd", "thesis_year": "2013" }, { "id": "thesis:7226", "collection": "thesis", "collection_id": "7226", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10072012-230900231", "primary_object_url": { "basename": "Nikil-Mehta-2013.pdf", "content": "final", "filesize": 1724373, "license": "other", "mime_type": "application/pdf", "url": "/7226/1/Nikil-Mehta-2013.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "An Ultra-Low-Energy, Variation-Tolerant FPGA Architecture Using Component-Specific Mapping", "author": [ { "family_name": "Mehta", "given_name": "Nikil", "clpid": "Mehta-Nikil" } ], "thesis_advisor": [ { "family_name": "DeHon", "given_name": "Andre", "clpid": "DeHon-A" } ], "thesis_committee": [ { "family_name": "Martin", "given_name": "Alain J.", "clpid": "Martin-A-J" }, { "family_name": "DeHon", "given_name": "Andre", "clpid": "DeHon-A" }, { "family_name": "Calhoun", "given_name": "Benton H.", "clpid": "Calhoun-B-H" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "As feature sizes scale toward atomic limits, parameter variation continues to increase, leading to increased margins in both delay and energy. Parameter variation both slows down devices and causes devices to fail. For applications that require high performance, the possibility of very slow devices on critical paths forces designers to reduce clock speed in order to meet timing. For an important and emerging class of applications that target energy-minimal operation at the cost of delay, the impact of variation-induced defects at very low voltages mandates the sizing up of transistors and operation at higher voltages to maintain functionality.
\r\n\r\nWith post-fabrication configurability, FPGAs have the opportunity to self-measure the impact of variation, determining the speed and functionality of each individual resource. Given that information, a delay-aware router can use slow devices on non-critical paths, fast devices on critical paths, and avoid known defects. By mapping each component individually and customizing designs to a component's unique physical characteristics, we demonstrate that we can eliminate delay margins and reduce energy margins caused by variation.
\r\n\r\nTo quantify the potential benefit we might gain from component-specific mapping, we first measure the margins associated with parameter variation, and then focus primarily on the energy benefits of FPGA delay-aware routing over a wide range of predictive technologies (45 nm--12 nm) for the Toronto20 benchmark set. We show that relative to delay-oblivious routing, delay-aware routing without any significant optimizations can reduce minimum energy/operation by 1.72x at 22 nm. We demonstrate how to construct an FPGA architecture specifically tailored to further increase the minimum energy savings of component-specific mapping by using the following techniques: power gating, gate sizing, interconnect sparing, and LUT remapping. With all optimizations considered we show a minimum energy/operation savings of 2.66x at 22 nm, or 1.68--2.95x when considered across 45--12 nm. As there are many challenges to measuring resource delays and mapping per chip, we discuss methods that may make component-specific mapping more practical. We demonstrate that a simpler, defect-aware routing achieves 70% of the energy savings of delay-aware routing. Finally, we show that without variation tolerance, scaling from 16 nm to 12 nm results in a net increase in minimum energy/operation; component-specific mapping, however, can extend minimum energy/operation scaling to 12 nm and possibly beyond.
\r\n", "doi": "10.7907/358S-CW22", "publication_date": "2013", "thesis_type": "phd", "thesis_year": "2013" }, { "id": "thesis:7286", "collection": "thesis", "collection_id": "7286", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:11262012-212534634", "primary_object_url": { "basename": "DSRussell_Thesis_2012.pdf", "content": "final", "filesize": 16046459, "license": "other", "mime_type": "application/pdf", "url": "/7286/1/DSRussell_Thesis_2012.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Technology Advances for Radio Astronomy", "author": [ { "family_name": "Russell", "given_name": "Damon Stuart", "clpid": "Russell-Damon-Stuart" } ], "thesis_advisor": [ { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" } ], "thesis_committee": [ { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Emami", "given_name": "Azita", "orcid": "0000-0002-6945-9958", "clpid": "Emami-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" }, { "family_name": "Gaier", "given_name": "Todd C.", "clpid": "Gaier-T-C" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The field of radio astronomy continues to provide fundamental contributions to the understanding of the evolution, and inner workings of, our universe. It has done so from its humble beginnings, where single antennas and receivers were used for observation, to today's focal plane arrays and interferometers. The number of receiving elements (pixels) in these instruments is quickly growing, currently approaching one hundred. For the instruments of tomorrow, the number of receiving elements will be in the thousands. Such instruments will enable researchers to peer deeper into the fabric of our universe and do so at faster survey speeds. They will provide enormous capability, both for unraveling today's mysteries as well as for the discovery of new phenomena.
\r\n \r\nAmong other challenges, producing the large numbers of low-noise amplifiers required for these instruments will be no easy task. The work described in this thesis advances the state of the art in three critical areas, technological advancements necessary for the future design and manufacturing of thousands of low-noise amplifiers. These areas being: the automated, cryogenic, probing of $\\diameter100$ mm indium phosphide wafers; a system for measuring the noise parameters of devices at cryogenic temperatures; and the development of low-noise, silicon germanium amplifiers for terahertz mixer receivers. The four chapters that comprise the body of this work detail the background, design, assembly, and testing involved in these contributions. Also included is a brief survey of noise parameters, the knowledge of which is fundamental to the design of low-noise amplifiers and the optimization of the system noise temperature for large, dense, interferometers.
", "doi": "10.7907/MW3P-2S22", "publication_date": "2013", "thesis_type": "phd", "thesis_year": "2013" }, { "id": "thesis:7644", "collection": "thesis", "collection_id": "7644", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04292013-140750287", "primary_object_url": { "basename": "Akgiray_PhDThesis_FinalVersion.pdf", "content": "final", "filesize": 22979327, "license": "other", "mime_type": "application/pdf", "url": "/7644/1/Akgiray_PhDThesis_FinalVersion.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "New Technologies Driving Decade-Bandwidth Radio Astronomy: Quad-ridged Flared Horn and Compound-Semiconductor LNAs", "author": [ { "family_name": "Akgiray", "given_name": "Ahmed Halid", "clpid": "Akgiray-Ahmed-Halid" } ], "thesis_advisor": [ { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "thesis_committee": [ { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" }, { "family_name": "Imbriale", "given_name": "William A.", "clpid": "Imbriale-W-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Among the branches of astronomy, radio astronomy is unique in that it spans the largest portion of the electromagnetic spectrum, e.g., from about 10 MHz to 300 GHz. On the other hand, due to scientific priorities as well as technological limitations, radio astronomy receivers have traditionally covered only about an octave bandwidth. This approach of \"one specialized receiver for one primary science goal\" is, however, not only becoming too expensive for next-generation radio telescopes comprising thousands of small antennas, but also is inadequate to answer some of the scientific questions of today which require simultaneous coverage of very large bandwidths.
\r\n\r\nThis thesis presents significant improvements on the state of the art of two key receiver components in pursuit of decade-bandwidth radio astronomy: 1) reflector feed antennas; 2) low-noise amplifiers on compound-semiconductor technologies. The first part of this thesis introduces the quadruple-ridged flared horn, a flexible, dual linear-polarization reflector feed antenna that achieves 5:1-7:1 frequency bandwidths while maintaining near-constant beamwidth. The horn is unique in that it is the only wideband feed antenna suitable for radio astronomy that: 1) can be designed to have nominal 10 dB beamwidth between 30 and 150 degrees; 2) requires one single-ended 50 Ohm low-noise amplifier per polarization. Design, analysis, and measurements of several quad-ridged horns are presented to demonstrate its feasibility and flexibility.
\r\n\r\nThe second part of the thesis focuses on modeling and measurements of discrete high-electron mobility transistors (HEMTs) and their applications in wideband, extremely low-noise amplifiers. The transistors and microwave monolithic integrated circuit low-noise amplifiers described herein have been fabricated on two state-of-the-art HEMT processes: 1) 35 nm indium phosphide; 2) 70 nm gallium arsenide. DC and microwave performance of transistors from both processes at room and cryogenic temperatures are included, as well as first-reported measurements of detailed noise characterization of the sub-micron HEMTs at both temperatures. Design and measurements of two low-noise amplifiers covering 1--20 and 8\u201450 GHz fabricated on both processes are also provided, which show that the 1--20 GHz amplifier improves the state of the art in cryogenic noise and bandwidth, while the 8--50 GHz amplifier achieves noise performance only slightly worse than the best published results but does so with nearly a decade bandwidth.
\r\n", "doi": "10.7907/TYX5-2C48", "publication_date": "2013", "thesis_type": "phd", "thesis_year": "2013" }, { "id": "thesis:7675", "collection": "thesis", "collection_id": "7675", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:05082013-113725728", "primary_object_url": { "basename": "loh_rui_yan_matthew_2013_thesis.pdf", "content": "final", "filesize": 9062229, "license": "other", "mime_type": "application/pdf", "url": "/7675/1/loh_rui_yan_matthew_2013_thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Dense, Efficient Chip-to-Chip Communication at the Extremes of Computing", "author": [ { "family_name": "Loh Rui Yan", "given_name": "Matthew", "clpid": "Loh-Rui-Yan-Matthew" } ], "thesis_advisor": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" } ], "thesis_committee": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Tai", "given_name": "Yu-Chong", "clpid": "Tai-Yu-Chong" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The scalability of CMOS technology has driven computation into a diverse range of applications across the power consumption, performance and size spectra. Communication is a necessary adjunct to computation, and whether this is to push data from node-to-node in a high-performance computing cluster or from the receiver of wireless link to a neural stimulator in a biomedical implant, interconnect can take up a significant portion of the overall system power budget. Although a single interconnect methodology cannot address such a broad range of systems efficiently, there are a number of key design concepts that enable good interconnect design in the age of highly-scaled CMOS: an emphasis on highly-digital approaches to solving \u2018analog\u2019 problems, hardware sharing between links as well as between different functions (such as equalization and synchronization) in the same link, and adaptive hardware that changes its operating parameters to mitigate not only variation in the fabrication of the link, but also link conditions that change over time. These concepts are demonstrated through the use of two design examples, at the extremes of the power and performance spectra.
\r\n\r\nA novel all-digital clock and data recovery technique for high-performance, high density interconnect has been developed. Two independently adjustable clock phases are generated from a delay line calibrated to 2 UI. One clock phase is placed in the middle of the eye to recover the data, while the other is swept across the delay line. The samples produced by the two clocks are compared to generate eye information, which is used to determine the best phase for data recovery. The functions of the two clocks are swapped after the data phase is updated; this ping-pong action allows an infinite delay range without the use of a PLL or DLL. The scheme's generalized sampling and retiming architecture is used in a sharing technique that saves power and area in high-density interconnect. The eye information generated is also useful for tuning an adaptive equalizer, circumventing the need for dedicated adaptation hardware.
\r\n\r\nOn the other side of the performance/power spectra, a capacitive proximity interconnect has been developed to support 3D integration of biomedical implants. In order to integrate more functionality while staying within size limits, implant electronics can be embedded onto a foldable parylene (\u2018origami\u2019) substrate. Many of the ICs in an origami implant will be placed face-to-face with each other, so wireless proximity interconnect can be used to increase communication density while decreasing implant size, as well as facilitate a modular approach to implant design, where pre-fabricated parylene-and-IC modules are assembled together on-demand to make custom implants. Such an interconnect needs to be able to sense and adapt to changes in alignment. The proposed array uses a TDC-like structure to realize both communication and alignment sensing within the same set of plates, increasing communication density and eliminating the need to infer link quality from a separate alignment block. In order to distinguish the communication plates from the nearby ground plane, a stimulus is applied to the transmitter plate, which is rectified at the receiver to bias a delay generation block. This delay is in turn converted into a digital word using a TDC, providing alignment information.
\r\n", "doi": "10.7907/FQ18-2X96", "publication_date": "2013", "thesis_type": "phd", "thesis_year": "2013" }, { "id": "thesis:7161", "collection": "thesis", "collection_id": "7161", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06122012-091920562", "type": "thesis", "title": "Superconducting Microwave Resonator Arrays for Submillimeter/Far-infrared Imaging", "author": [ { "family_name": "Noroozian", "given_name": "Omid", "clpid": "Noroozian-Omid" } ], "thesis_advisor": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" } ], "thesis_committee": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" }, { "family_name": "Golwala", "given_name": "Sunil", "clpid": "Golwala-S-R" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "Caltech Submillimeter Observatory" }, { "literal": "Astronomy Department" }, { "literal": "div_eng" } ], "abstract": "Superconducting microwave resonators have the potential to revolutionize submillimeter and far-infrared astronomy, and with it our understanding of the universe. The field of low-temperature detector technology has reached a point where extremely sensitive devices like transition-edge sensors are now capable of detecting radiation limited by the background noise of the universe. However, the size of these detector arrays are limited to only a few thousand pixels. This is because of the cost and complexity of fabricating large-scale arrays of these detectors that can reach up to 10 lithographic levels on chip, and the complicated SQUID-based multiplexing circuitry and wiring for readout of each detector. In order to make substantial progress, next- generation ground-based telescopes such as CCAT or future space telescopes require focal planes with large-scale detector arrays of 104\u2013106 pixels. Arrays using microwave kinetic inductance detectors (MKID) are a potential solution. These arrays can be easily made with a single layer of superconducting metal film deposited on a silicon substrate and pattered using conventional optical lithography. Furthermore, MKIDs are inherently multiplexable in the frequency domain, allowing \u223c 103 detectors to be read out using a single coaxial transmission line and cryogenic amplifier, drastically reducing cost and complexity.
\r\n\r\nAn MKID uses the change in the microwave surface impedance of a superconducting thin-film microresonator to detect photons. Absorption of photons in the superconductor breaks Cooper pairs into quasiparticles, changing the complex surface impedance, which results in a perturbation of resonator frequency and quality factor. For excitation and readout, the resonator is weakly coupled to a transmission line. The complex amplitude of a microwave probe signal tuned on-resonance and transmitted on the feedline past the resonator is perturbed as photons are absorbed in the superconductor. The perturbation can be detected using a cryogenic amplifier and subsequent homodyne mixing at room temperature. In an array of MKIDs, all the resonators are coupled to a shared feedline and are tuned to slightly different frequencies. They can be read out simultaneously using a comb of frequencies generated\r\nand measured using digital techniques.
\r\n\r\nThis thesis documents an effort to demonstrate the basic operation of \u223c 256 pixel arrays of lumped-element MKIDs made from superconducting TiNx on silicon. The resonators are designed and simulated for optimum operation. Various properties of the resonators and arrays are measured and compared to theoretical expectations. A particularly exciting observation is the extremely high quality factors (\u223c 3 \u00d7 107) of our TiNx resonators which is essential for ultra-high sensitivity. The arrays are tightly packed both in space and in frequency which is desirable for larger full-size arrays. However, this can cause a serious problem in terms of microwave crosstalk between neighboring pixels. We show that by properly designing the resonator geometry, crosstalk can be eliminated; this is supported by our measurement results. We also tackle the problem of excess frequency noise in MKIDs. Intrinsic noise in the form of an excess resonance frequency jitter exists in planar superconducting resonators that are made on dielectric substrates. We conclusively show that this noise is due to fluctuations of the resonator capacitance. In turn, the capacitance fluctuations are thought to be driven by two-level system (TLS) fluctuators in a thin layer on the surface of the device. With a modified resonator design we demonstrate with measurements that this noise can be substantially reduced. An optimized version of this resonator was designed for the multiwavelength submillimeter kinetic inductance camera (MUSIC) instrument for the Caltech Submillimeter Observatory.
", "doi": "10.7907/8MG2-NB23", "publication_date": "2012", "thesis_type": "phd", "thesis_year": "2012" }, { "id": "thesis:7163", "collection": "thesis", "collection_id": "7163", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06122012-144158047", "primary_object_url": { "basename": "JuhwanYoo-thesis-update.pdf", "content": "updated", "filesize": 5048489, "license": "other", "mime_type": "application/pdf", "url": "/7163/2/JuhwanYoo-thesis-update.pdf", "version": "v8.0.0" }, "type": "thesis", "title": "Compressed Sensing Receivers: Theory, Design, and Performance Limits", "author": [ { "family_name": "Yoo", "given_name": "Juhwan", "clpid": "Yoo-Juhwan" } ], "thesis_advisor": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" } ], "thesis_committee": [ { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Candes", "given_name": "Emmanuel J.", "clpid": "Candes-E-J" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Hassibi", "given_name": "Babak", "clpid": "Hassibi-B" }, { "family_name": "Tropp", "given_name": "Joel A.", "clpid": "Tropp-J-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The past 50 years have seen tremendous developments in electronics due to the rise and rapid development of IC-fabrication technology [1]. In addition to the production of cheap and abundant computing resources, another area of rapid advancement has been wireless technologies. While the central focus of wireless research has been mobile communication, an area of increasing importance concerns the development of sensing/spectral applications over bandwidths exceeding multiple GHz. Such systems have many applications ranging from scientific to military. Although some solutions exist, their large size, weight, and power make more-efficient solutions desirable.
\r\n\r\nAt present, one of the principal bottlenecks in designing such systems is the power consumption of the back-end ADCs at the required digitization rate. ADCs are a dominant source of power consumption; it is also often the case that ADC block specifications are used to determine parameters for the rest of the signal chain, such as the RF front-end and the DSP-core which processes the digitized samples [2]. Historically, increases in system bandwidth have come from developing ADCs with superior performance.
\r\n\r\nIn contrast to improving ADC performance, this work presents a system-level approach with the goal of minimizing the required digitization rate for observation of a given effective instantaneous bandwidth (EIBW). The approach was inspired by the field of compressed sensing [3\u20135]. Loosely stated, CS asserts that samples which represent random projections can be used to recover sparse and/or compressible signals with what was previously thought to be insufficient information. The primary contributions of this thesis include: the establishment of physical feasibility of CS-based receivers through implementation of the first fully-integrated high speed CS-based front-end known as the random-modulation pre-integrator (RMPI) [6\u20139], and the development of a principled design methodology based on a rigorous analytical and empirical feasibility study of the system.
\r\n\r\nThe 8-channel RMPI was implemented in 90 nm CMOS and was validated by physical measurements of the fabricated chip. The implemented RMPI achieves an EIBW of 2 GHz, with > 54 dB of dynamic range. Most notably, the aggregate digitization rate is fs = 320 Msps, 12.5\u00d7 lower than the Nyquist rate.
\r\n\r\n", "doi": "10.7907/Y3FA-VB87", "publication_date": "2012", "thesis_type": "phd", "thesis_year": "2012" }, { "id": "thesis:6765", "collection": "thesis", "collection_id": "6765", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:01082012-184435123", "primary_object_url": { "basename": "Bohn_Thesis_edit2_export.pdf", "content": "final", "filesize": 4637504, "license": "other", "mime_type": "application/pdf", "url": "/6765/1/Bohn_Thesis_edit2_export.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Integrated Circuit Signal Generation and Detection Techniques for Microwave and Sub-Millimeter Wave Signals", "author": [ { "family_name": "Bohn", "given_name": "Florian", "clpid": "Bohn-Florian" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Chattopadhyay", "given_name": "Goutam", "clpid": "Chattopadhyay-G" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The unabated reduction of device feature sizes in semiconductor processes, particularly in complementary metal-oxide semiconductor (CMOS) processes, has served as the enabling factor behind integrated electronic systems of ever increasing complexity and speeds. As a result, former niche market applications, such as the global-positioning system (GPS), cellular telephony or powerful general purpose computers, have expanded into the field of consumer electronics with tremendous impact on the daily lives of millions of people. It is, therefore, only logical that the future will bring new applications to the mass market that today only exist as niche applications.\r\nSystems operating in the millimeter wave frequency range are an example of a current niche market, with current research striving to fully integrate such systems using advanced semiconductor processing technology. Electromagnetic waves at these frequencies become comparable in size to the electronics circuits. This opens the possibility for novel design approaches that were traditionally not available to integrated circuit radio-frequency designers. On the other hand, the increase in the number of available devices also brings with it new challenges due to increasing variability in device performance. Self-correcting techniques for integrated circuits that offset this increased variability are therefore also highly desirable.
\r\n\r\nIn this dissertation, we explore the above issues on several fronts. We will first present a phase-locked loop synthesizer that auto-corrects its spurious output tones as an example of circuits that correct for a parasitic effect by leveraging the availability of many active devices to construct a digital feedback loop. We will then focus on the effort to operate CMOS integrated circuits in the terahertz regime by developing a solid design foundation for converting signals to frequencies beyond the maximum power gain frequency\u3016 f\u3017_max. We will use the insights gained to develop and explore two designs generating power at these high frequencies as proofs of concept. Finally, we will focus on the passive electromagnetic components of such high frequency systems and present a novel way of designing electromagnetic structures that are comparable to the wavelength size in integrated systems by introducing the third physical dimension into the design process for integrated electromagnetic structures.
\r\n", "doi": "10.7907/Q018-QP18", "publication_date": "2012", "thesis_type": "phd", "thesis_year": "2012" }, { "id": "thesis:7158", "collection": "thesis", "collection_id": "7158", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:06112012-145654043", "type": "thesis", "title": "Silicon-Based Terahertz Circuits and Systems", "author": [ { "family_name": "Sengupta", "given_name": "Kaushik", "clpid": "Sengupta-Kaushik" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Choo", "given_name": "Hyuck", "clpid": "Choo-Hyuck" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The Terahertz frequency range, often referred to as the `Terahertz' gap, lies wedged between microwave at the lower end and infrared at the higher end of the spectrum, occupying frequencies between 0.3-3.0 THz. For a long time, applications in THz frequencies had been limited to astronomy and chemical sciences, but with advancement in THz technology in recent years, it has shown great promise in a wide range of applications ranging from disease diagnostics, non-invasive early skin cancer detection, label-free DNA sequencing to security screening for concealed weapons and contraband detection, global environmental monitoring, nondestructive quality control and ultra-fast wireless communication. Up until recently, the terahertz frequency range has been mostly addressed by high mobility compound III-V processes, expensive nonlinear optics, or cryogenically cooled quantum cascade lasers. A low cost, room temperature alternative can enable the development of such a wide array of applications, not currently accessible due to cost and size limitations. In this thesis, we will discuss our approach towards development of integrated terahertz technology in silicon-based processes. In the spirit of academic research, we will address frequencies close to 0.3 THz as 'Terahertz'.
\r\n\r\nIn this thesis, we address both fronts of integrated THz systems in silicon: THz power generation, radiation and transmitter systems, and THz signal detection and receiver systems. THz power generation in silicon-based integrated circuit technology is challenging due to lower carrier mobility, lower cut-o frequencies compared to compound III-V processes, lower breakdown voltages and lossy passives. Radiation from silicon chip is also challenging due to lossy substrates and high dielectric constant of silicon. In this work, we propose novel ways of combining circuit and electromagnetic techniques in a holistic design approach, which can overcome limitations of conventional block-by-block or partitioned design methodology, in order to generate high-frequency signals above the classical definition of cut-off frequencies (\u0192t/\u0192max). We demonstrate this design philosophy in an active electromagnetic structure, which we call Distributed Active Radiator. It is inspired by an Inverse\r\nMaxwellian approach, where instead of using classical circuit and electromagnetic blocks to generate and radiate THz frequencies, we formulate surface (metal) currents in silicon chip for a desired THz field prole and develop active means of controlling different harmonic\r\ncurrents to perform signal generation, frequency multiplication, radiation and lossless filtering, simultaneously in a compact footprint. By removing the articial boundaries between circuits, electromagnetics and antenna, we open ourselves to a broader design space. This\r\nenabled us to demonstrate the rst 1 mW Eective-isotropic-radiated-power(EIRP) THz (0.29 THz) source in CMOS with total radiated power being three orders of magnitude more than previously demonstrated. We also proposed a near-field synchronization mechanism, which is a scalable method of realizing large arrays of synchronized autonomous radiating sources in silicon. We also demonstrate the first THz CMOS array with digitally controlled beam-scanning in 2D space with radiated output EIRP of nearly 10 mW at 0.28 THz.
\r\n\r\nOn the receiver side, we use a similar electronics and electromagnetics co-design approach to realize a 4x4 pixel integrated silicon Terahertz camera demonstrating to the best of our knowledge, the most sensitive silicon THz detector array without using post-processing,\r\nsilicon lens or high-resistivity substrate options (NEP < 10 pW √ Hz at 0.26 THz). We put the 16 pixel silicon THz camera together with the CMOS DAR THz power generation arrays and demonstrated, for the first time, an all silicon THz imaging system with a CMOS source.
", "doi": "10.7907/MBXB-6R29", "publication_date": "2012", "thesis_type": "phd", "thesis_year": "2012" }, { "id": "thesis:6005", "collection": "thesis", "collection_id": "6005", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:08232010-071647727", "type": "thesis", "title": "Techniques for Mixed-Signal Linearization and Large Signal Handling in Radio-Frequency Receiver Circuits", "author": [ { "family_name": "Keehr", "given_name": "Edward Arthur", "clpid": "Keehr-Edward-Arthur" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hassibi", "given_name": "Babak", "clpid": "Hassibi-B" }, { "family_name": "D'Addario", "given_name": "Larry R.", "clpid": "D'Addario-L-R" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "In this dissertation, two effective linearization schemes for radio-frequency receivers are introduced. The first of these comprises a mixed-signal feedforward path which regenerates third-order intermodulation (IM3) products at radio frequencies, downconverts these products, digitizes them, and then uses them to cancel corruptive IM3 products in the digital baseband portion of a nominally linear receiver path. The combined implemented receiver represents a SAW-less direct-conversion receiver for UMTS FDD Region 1 that achieves an uncorrected out-of-band IIP3 of -7.1dBm under worst-case blocking specifications. Under IM3 equalization, the receiver achieves an effective IIP3 of +5.3dBm and meets the UMTS BER sensitivity requirements with 3.7dB of margin. To enable this mixed-signal feedforward path, a multistage cubic term generator is introduced which uses cascaded nonlinear operations to generate reference IM3 products. The multistage nature of this circuit is considered in the context of the aforementioned linearization scheme and is shown to provide sufficient dynamic range for nearly complete IM3 cancellation while dissipating far less power than the original receiver front end. In particular, the effect of the group delay between stages is analyzed and shown to permit large IM3 cancellation ratios for interstage group delays less than 1ns.
\r\n\r\nExpanding upon the first effective linearization approach led to the development of a large signal handling receiver with an out-of-band 1-dB desensitization point of +12.5dBm. Enabling this large signal handling capability is a passive mixer downconverter preceded by a novel wide-swing LNTA. With a stacked push-pull class-AB common-gate architecture, the LNTA reduces the magnitude of input-referred distortion by up to 40dB beyond that predicted by an initial slope-of-3 characteristic while at the same time minimally impacting the effective small-signal gain of the receiver. To compensate for intermodulation distortion terms of order greater than 3, IM3 and IM2 products are processed down to digital baseband where they are successively multiplied to generate approximations to higher-order terms. In the case of a +12.4dBm QPSK-modulated signal and a -16.3dBm CW blocker, cancellation improves receiver input-referred error by over 24dB, resulting in an extrapolated IIP3 of +43.5dBm.
", "doi": "10.7907/WFGT-4823", "publication_date": "2011", "thesis_type": "phd", "thesis_year": "2011" }, { "id": "thesis:6364", "collection": "thesis", "collection_id": "6364", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:04292011-221312708", "type": "thesis", "title": "Optoelectronic Control of the Phase and Frequency of Semiconductor Lasers", "author": [ { "family_name": "Satyan", "given_name": "Naresh", "clpid": "Satyan-Naresh" } ], "thesis_advisor": [ { "family_name": "Yariv", "given_name": "Amnon", "clpid": "Yariv-A" } ], "thesis_committee": [ { "family_name": "Yariv", "given_name": "Amnon", "clpid": "Yariv-A" }, { "family_name": "Crosignani", "given_name": "Bruno", "clpid": "Crosignani-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "This thesis explores the precise control of the phase and frequency of the output of semiconductor lasers (SCLs), which are the basic building blocks of most modern optical communication networks. Phase and frequency control is achieved by purely electronic means, using SCLs in optoelectronic feedback systems, such as optical phase-locked loops (OPLLs) and optoelectronic swept-frequency laser (SFL) sources. Architectures and applications of these systems are studied.
\r\n\r\nOPLLs with single-section SCLs have limited bandwidths due to the nonuniform SCL frequency modulation (FM) response. To overcome this limitation, two novel OPLL architectures are designed and demonstrated, viz. (i) the sideband-locked OPLL, where the feedback into the SCL is shifted to a frequency range where the FM response is uniform, and (ii) composite OPLL systems, where an external optical phase modulator corrects excess phase noise. It is shown, theoretically and experimentally, and in the time and frequency domains, that the coherence of the master laser is \u201ccloned\u201d onto the slave SCL in an OPLL. An array of SCLs, phase-locked to a common master, therefore forms a coherent aperture, where the phase of each emitter is electronically controlled by the OPLL. Applications of phase-controlled apertures in coherent power-combining and all-electronic beam-steering are demonstrated.
\r\n\r\nAn optoelectronic SFL source that generates precisely linear, broadband, and rapid frequency chirps (several 100 GHz in 0.1 ms) is developed and demonstrated using a novel OPLL-like feedback system, where the frequency chirp characteristics are determined solely by a reference electronic oscillator. Results from high-sensitivity biomolecular sensing experiments utilizing the precise frequency control are reported. Techniques are developed to increase the tuning range of SFLs, which is the primary requirement in high-resolution three-dimensional imaging applications. These include (i) the synthesis of a larger effective bandwidth for imaging by \"stitching\" measurements taken using SFLs chirping over different regions of the optical spectrum; and (ii) the generation of a chirped wave with twice the chirp bandwidth and the same chirp characteristics by nonlinear four-wave mixing of the SFL output and a reference monochromatic wave. A quasi-phase-matching scheme to overcome dispersion in the nonlinear medium is described and implemented.
\r\n", "doi": "10.7907/24DM-VW62", "publication_date": "2011", "thesis_type": "phd", "thesis_year": "2011" }, { "id": "thesis:5233", "collection": "thesis", "collection_id": "5233", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06102009-164232", "primary_object_url": { "basename": "Thesis.pdf", "content": "final", "filesize": 10103965, "license": "other", "mime_type": "application/pdf", "url": "/5233/1/Thesis.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Precision Frequency and Phase Synthesis Techniques in Integrated Circuits for Biosensing, Communication and Radar", "author": [ { "family_name": "Wang", "given_name": "Hua", "orcid": "0000-0003-4952-5505", "clpid": "Wang-Hua" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Scherer", "given_name": "Axel", "clpid": "Scherer-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Today\u2019s CMOS technology provides circuit designers with a powerful implementation platform that supports innovation opportunities on both circuit-topology and system-architecture levels. Moreover, the versatility of CMOS implementation opens the door for a plethora of challenging and exciting interdisciplinary research.
\r\n\r\nThis dissertation focuses on investigating novel techniques and applications for precision frequency and phase synthesis in CMOS. It consists of two parts: a CMOS compatible molecular-level biosensor and a multiple-beam/multi-band scalable CMOS phased array receiver system.
\r\n\r\nIn the first part, a frequency shift based magnetic biosensing scheme is introduced to address the Point-of-Care (PoC) biomolecular diagnosis for high-sensitivity, portable and cost low applications. Compared with existing biosensing schemes, the proposed scheme achieves a competitive sensitivity without using optical devices, external biasing fields or expensive post-processing steps. A discrete implementation first verifies the sensing mechanism and reveals several design insights. An integrated implementation based on standard 130nm CMOS process is then designed with differential sensing and temperature controlling schemes. Overall, with a differential uncertainty of 0.13ppm for relative frequency shift, the sensor achieves reliable detection of one single micron-size magnetic particle (D=4.5um, 2.4um and 1um) as well as 1n-Molar real DNA samples labeled by magnetic nanoparticles (D=50nm).
\r\n\r\nIn the second part, a high-resolution compensation technique is proposed to address mismatch and offset issues encountered by practical phased array system. It employs a dense Cartesian interpolation scheme with an easily scalable architecture and a wide operation bandwidth. As an implementation example, a 6-to-18GHz dual-band quad-beam phased array CMOS receiver is presented, which is capable of forming four spatially independent beams at two different frequencies across the tritave bandwidth. With the mismatch compensation, the array element has achieved a maximum RMS phase error of 0.5\u02da with an RMS amplitude variation less than 1.5dB for the 360\u02da interpolation over the full operation bandwidth. For a 4-element phased array receiver system based on the designed CMOS chip, the electrical array pattern is measured at 6GHz, 10.4GHz and 18GHz, with the worst case peak-to-null ratio of 21.5dB. In addition, a broadband inductorless design methodology based on Cherry-Hooper topology is proposed for chip area saving. As implementation examples, we will show a DC-19GHz 10dB gain broadband buffer amplifier, a DC-12GHz broadband phase rotator with 10-bit resolution and a beam-forming network in a 10.4GHz to 18GHz phased array receiver chip with dual-beam capability.
", "doi": "10.7907/T4EC-TX97", "publication_date": "2009", "thesis_type": "phd", "thesis_year": "2009" }, { "id": "thesis:5179", "collection": "thesis", "collection_id": "5179", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-03292009-070752", "primary_object_url": { "basename": "Thesis-yujiu-final-20090331.pdf", "content": "final", "filesize": 3325286, "license": "other", "mime_type": "application/pdf", "url": "/5179/1/Thesis-yujiu-final-20090331.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Circuits and Systems for Wireless Concurrent Communication", "author": [ { "family_name": "Wang", "given_name": "Yu-Jiu", "orcid": "0000-0002-2534-1069", "clpid": "Wang-Yu-Jiu" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Vaidyanathan", "given_name": "P. P.", "clpid": "Vaidyanathan-P-P" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Concurrency is a special kind of analog circuit parallelism that uses a single circuit with necessary bandwidth to process multiple signals at the same time. Concurrent radios offer a higher data rate and improved system diversity. Our comprehensive treatment comprises proposals for potential transceiver architectures, invention of circuit blocks, and provisions of innovative analysis methods.
\r\n\r\nThe analysis of concurrent circuits are often complex. To simplify noise analysis, a R^(N^2 )-vector space is first proposed to re-formulate the N-port network noise modeling problem. Any internal physical source inside the noisy network contributes a small vector in the defined R^(N^2)-vector space, and the aggregate statistical behavior of this noisy network can be viewed as the vector sum of these vectors. Applying this concept to FET noise modeling leads to several modified FET noise models, in which three uncorrelated noise sources are sufficient to describe the statistical behavior of an intrinsic FET. The use of these new FET models can simplify the analysis, simulation, and optimization of low noise systems without sacrificing accuracy.
\r\n\r\nBroadband low-noise amplifier is a critical block in concurrent receiver systems. We propose a novel low-noise weighted distributed amplifier (WDA) topology, which uses the internal finite-impulse-response filtering inside a conventional distributed amplifier to partially suppress internal thermal noise. A distinct advantage of this topology is its tolerance to input parasitic capacitance which can be used to provide good electro-static discharge (ESD) protection without sacrificing its noise performance and power consumption. A compact 3.1\u250010.6 GHz WDA IC is built on a 130 nm CMOS process. Experimental results show 2.3\u25004.5 dB NF at 23 mW power consumption.
\r\n\r\nUsing concurrency in wireless link can boost communication data rate. As a proof-of concept, we propose dynamically scalable concurrent communication by dividing the 7.5 GHz bandwidth of the unlicensed 3.1\u250010.6 GHz spectrum into seven concurrent channels. A CMOS octa-core RF receiver is implemented to validate the idea. Based on the receiver measurement results, a wireless link can be built to achieve a 16 Gbps channel limit at five meter TX-RX distance at 400 mW power consumption.
\r\n\r\nTunable concurrency can improve the receiver diversity. A prototype 6\u250018 GHz concurrent tunable dual-band phased array receiver element IC is proposed and built on a 130 nm CMOS process. Experimental results demonstrate successful dual-band RF reception within a low band (6\u250010.4 GHz) and high band (10.4\u250018 GHz) with 300 MHz baseband bandwidth. A final four-element phased array receiver built from the prototyped ICs shows an array pattern with worst-case 21 dB peak-to-null ratio across all frequencies.
\r\n\r\nConcurrency can also be used to achieve multi-beam reception by providing multiple phase-shifts for each RF signals and combining them separately at baseband outputs. A 10.4\u250018 GHz concurrent dual-beam phased array receiver is proposed based on this concept, and is implemented on a 130 nm CMOS process. A final four-element phased array system shows successful concurrent dual-beam reception at the same RF frequency.
Yu-Jiu Wang (209\r\n", "doi": "10.7907/FZ1R-MJ30", "publication_date": "2009", "thesis_type": "phd", "thesis_year": "2009" }, { "id": "thesis:2531", "collection": "thesis", "collection_id": "2531", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06092009-113849", "primary_object_url": { "basename": "Bardin_thesis_final.PDF", "content": "final", "filesize": 7572900, "license": "other", "mime_type": "application/pdf", "url": "/2531/1/Bardin_thesis_final.PDF", "version": "v2.0.0" }, "type": "thesis", "title": "Silicon-Germanium Heterojunction Bipolar Transistors for Extremely Low-Noise Applications", "author": [ { "family_name": "Bardin", "given_name": "Joseph Cheney", "orcid": "0000-0002-6523-6730", "clpid": "Bardin-Joseph-Cheney" } ], "thesis_advisor": [ { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "thesis_committee": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Historically speaking, the world of extremely low-noise solid-state amplification has been dominated by exotic technologies such as InP and GaAs HEMTs. By cryogenically cooling these devices, it is possible to realize microwave amplifiers with noise temperatures as low as 5K over decades of bandwidth. Although HEMTs can provide very low noise amplification when cooled to cryogenic temperatures, their radiometer performance is limited by intrinsic transconductance fluctuations. It is believed that bipolar devices do not suffer from this problem. As industry has invested more and more money into silicon based technologies, silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) have continued to improve and are now at the point where they are beginning to become competitive with InP HEMTs for microwave cryogenic low-noise amplifiers. Although extremely high frequency device operation has been observed at cryogenic temperatures, little work has been done on modeling the noise of cooled SiGe HBTs.
\r\n\r\nIn this report, a thorough investigation into the theoretical and practical aspects of using silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) for extremely low-noise applications is presented. The dissertation is broken up into three sections:
\r\n\r\n1) Background information: The fundamentals of SiGe HBTs are presented along with a discussion of how the properties of semiconductors change at cryogenic temperatures, as well the impact that these changes have on the performance of the devices.
\r\n\r\n2) Modeling: A comprehensive study of seven state-of-the-art HBTs at temperatures ranging from 18 K to 300 K is presented. The devices are compared in terms of dc, small-signal, and noise performance, and small-signal noise models are extracted. The section concludes with a brief summary of the important conclusions regarding the performance of SiGe devices at cryogenic temperatures.
\r\n\r\n3) Applications: The models developed previously are applied to the design of several state-of-the-art LNAs in both MMIC and discrete form. Noise performance better than 2 K is achieved in the low-GHz range, which is comparable to the best InP results. The section concludes with a discussion of some high-impedance differential amplifiers which have recently been fabricated.
\r\n", "doi": "10.7907/MCPE-4M30", "publication_date": "2009", "thesis_type": "phd", "thesis_year": "2009" }, { "id": "thesis:5227", "collection": "thesis", "collection_id": "5227", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06082008-174204", "primary_object_url": { "basename": "AydinBabakhaniThesis.pdf", "content": "final", "filesize": 7140526, "license": "other", "mime_type": "application/pdf", "url": "/5227/1/AydinBabakhaniThesis.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Direct Antenna Modulation (DAM) for On-Chip mm-Wave Transceivers", "author": [ { "family_name": "Babakhani", "given_name": "Aydin", "orcid": "0000-0001-8123-9061", "clpid": "Babakhani-Aydin" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Emami", "given_name": "Azita", "clpid": "Emami-A" }, { "family_name": "Hassibi", "given_name": "Babak", "clpid": "Hassibi-B" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "In the last few decades the puissant desire to miniaturize the digital circuits to achieve higher speed and larger density has shaped the evolution of the silicon-based technologies. This development opens a new era in the field of millimeter-wave electronics in which many low-cost high-yield silicon-based transistors can be used on a single chip to enable creation of novel architectures with unique properties not achievable with old processes. In addition to this high level of integration capability, the die size of comparable or even larger than the wave-length makes it possible to integrate antennas, transceivers, and digital circuitry all on a single silicon die.
\r\n\r\nIt is important to realize that although smaller parasitic capacitors and shorter transistor channels have improved fT and fmax of transistors, extremely thin metal layers, highly doped substrates, and low breakdown voltage transistors have severely affected the performance of analog and RF building blocks. For example, thin metal layers have increased the loss and lowered the quality factor of the building blocks such as capacitors and inductors and low breakdown voltage transistors have made the power generation quite challenging. Additionally, if not carefully designed, small wave-lengths in the millimeter-wave range may cause unintended radiation by on-chip components. In this dissertation, we address these issues in design of millimeter-wave silicon-based single-chip phased-array transceivers with integrated antennas. We also introduce the technique of Direct Antenna Modulation (DAM) and implement two proof-of-concept chips operating at 60 GHz.
\r\n\r\nWe will present the receiver and the on-chip antenna sections of a fully integrated 77 GHz four-element phased-array transceiver with on-chip antennas in silicon. The receiver section of the chip includes the complete down-conversion path comprising low-noise amplifier (LNA), frequency synthesizer, phase rotators, combining amplifiers, and on-chip dipole antennas. The signal combining is performed using a novel distributed active combining amplifier at an IF of 26 GHz. In the LO path, the output of the 52 GHz VCO is routed to different elements and can be phase shifted locally by the phase rotators. A silicon lens on the backside is used to reduce the loss due to the surface-wave power of the silicon substrate. Our measurements show a single-element LNA gain of 23 dB and a noise figure of 6.0 dB. Each of the four receive paths has a gain of 37 dB and a noise figure of 8.0 dB. Each on-chip antenna has a gain of +8 dBi.
\r\n\r\nA direct antenna modulation (DAM) technique is also introduced, where the radiated far-field signal is modulated by time-varying changes in the antenna near-field electromagnetic (EM) boundary conditions. This enables the transmitter to send data in a direction-dependent fashion producing a secure communication link. The transmitter architecture makes it possible to use narrow-band highly-efficient switching power amplifiers to transmit wideband constant and non-constant envelope modulated signals. Theoretically, these systems are capable of transmitting independent data in multiple directions at full-rate concurrently using a single transmitter. Direct antenna modulation (DAM) can be performed by using either switches or varactors. Two proof-of-concept DAM transmitters operating at 60GHz using switches and varactors are demonstrated in silicon proving the feasibility of this approach.
", "doi": "10.7907/BS6T-1S20", "publication_date": "2008", "thesis_type": "phd", "thesis_year": "2008" }, { "id": "thesis:5185", "collection": "thesis", "collection_id": "5185", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05092008-093609", "primary_object_url": { "basename": "Rassul_Karabalin_Thesis.pdf", "content": "final", "filesize": 15538339, "license": "other", "mime_type": "application/pdf", "url": "/5185/1/Rassul_Karabalin_Thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Nonlinear, Coupled, and Parametric Nanoelectromechanical Systems", "author": [ { "family_name": "Karabalin", "given_name": "Rassul", "clpid": "Karabalin-Rassul" } ], "thesis_advisor": [ { "family_name": "Roukes", "given_name": "Michael Lee", "clpid": "Roukes-M-L" } ], "thesis_committee": [ { "family_name": "Roukes", "given_name": "Michael Lee", "clpid": "Roukes-M-L" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Bockrath", "given_name": "Marc William", "clpid": "Bockrath-M-W" }, { "family_name": "Cross", "given_name": "Michael Clifford", "clpid": "Cross-M-C" } ], "local_group": [ { "literal": "div_pma" } ], "abstract": "Advances in nanoscience and nanotechnology hold enormous promises to benefit humankind in basic research, industry, and everyday life. One particular class of the vast field of nanodevices is resonant nanoelectromechanical systems (NEMS), which have recently attracted considerable research interest. While many of obstacles have been overcome in fundamental physics and engineering research of NEMS, intriguing questions and technological challenges remain unmet. This thesis is primarily focused on the studies of parametric, nonlinear, and coupled NEMS resonators.
\r\n\r\nIn this work the first very high-frequency (VHF) nanomechanical degenerate parametric amplifiers have been demonstrated by employing both magnetomotive and piezoelectric parametric pumping. A mechanical gain of 1000 and quality factor enhancement of 75 have been achieved. Such parametric resonators and nanomechanical amplification make it possible to evade the often-dominant transducer and amplifier noise, thus offering possibilities for improving the sensitivity of NEMS sensors, for exploring mechanical-domain signal processing, and for noise squeezing in precision physics measurements.
\r\n\r\nThe thesis also focuses on the rich dynamics and physics of coupled NEMS resonators. First, the major mechanisms of coupling are investigated both experimentally and analytically. The formalism for characterizing a new basis of vibration modes for strongly coupled nanoresonators is developed and experimentally demonstrated for systems with two, three and ten NEMS devices. By employing a pair of coupled resonators for long-term drift compensation, considerable improvement in resonator frequency stability is demonstrated. Simple linear interaction in nonlinear nanomechanical resonators is shown to generate remarkably complex and rich behavior including spontaneous state transition and chaos.
\r\n\r\nFinally, the complexity of the system is further increased when coupled and parametric effects are combined. A novel nanomechanical amplification mechanism has been discovered, based on the dynamical changes that an input signal induces in the topology of a bifurcation diagram of a system of two weakly coupled parametric resonators. Another interesting phenomenon\u2014nondegenerate parametric NEMS amplification is demonstrated in the case of strong coupling. This is a promising route to low noise mechanical displacement sensing because it not only provides a fundamentally noiseless amplification mechanism, but also it decouples pump and signal frequency.
", "doi": "10.7907/4GR5-3517", "publication_date": "2008", "thesis_type": "phd", "thesis_year": "2008" }, { "id": "thesis:2367", "collection": "thesis", "collection_id": "2367", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06012007-130844", "primary_object_url": { "basename": "Arun_Natarajan_Thesis.pdf", "content": "final", "filesize": 42998359, "license": "other", "mime_type": "application/pdf", "url": "/2367/1/Arun_Natarajan_Thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Millimeter-Wave Phased Arrays in Silicon", "author": [ { "family_name": "Natarajan", "given_name": "Arun Sridhar", "clpid": "Natarajan-Arun-Sridhar" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "D'Addario", "given_name": "Larry R.", "clpid": "D'Addario-L-R" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Integration of mm-wave multiple-antenna systems on silicon-based processes enables complex, low-cost systems for high-frequency communication and sensing applications. While individual silicon devices struggle to achieve the same performance as III-V semiconductor-based transistors at mm-wave frequencies, the benefits of integration, such as good component matching and near-zero incremental device cost, can be leveraged to achieve good system performance. This dissertation presents different techniques and architectures for integrating mm-wave phased arrays on commercial silicon process technologies by demonstrating phased-array transmitters and receivers at 24GHz, 60GHz, and 77GHz, in CMOS and SiGe BiCMOS processes.
\r\n\r\nInitially, the tradeoffs of high-frequency systems are discussed in the context of Shannon capacity and the benefits of integrating phased arrays at such high frequencies are discussed in detail. An analysis of the output noise in a phased-array receiver in the presence of antenna coupling and input noise correlation is carried out and measurements on a discrete two-element array demonstrate the dependence of output noise on the phase-shift setting.
\r\n\r\nThe design of the first fully-integrated 24GHz phased-array transmitter using mainly 0.18[mu]m CMOS transistors is described. The four-element array adopts a centralized LO-path phase-shifting approach using a multi-phase VCO. The on-chip 19.2GHz VCO generates 16 equally spaced LO phases leading to 7 degree beam resolution for radiation normal to the array. The transmitter includes four on-chip CMOS power amplifiers, with outputs matched to 50 Ohms, that are each capable of generating up to 14.5dBm of output power at 24GHz. The array achieves a peak-to-null ratio of 23dB with four elements active and can support data rates of 500Mb/s on each channel (with BPSK modulation) while occupying 6.8mm x 2.1mm of die area.
\r\n\r\nA high-resolution local LO-path phase-shifting architecture is presented as part of the first fully-integrated 77GHz phased-array transceiver in a SiGe BiCMOS process. The SiGe transceiver includes four transmit and four receive elements (including 77GHz LNA and PA), along with the LO frequency generation and distribution circuitry. The local LO-path phase-shifting scheme enables a robust distribution network that scales well with increasing frequency and/or number of elements, while providing high-resolution phase shifts. Each transmit element of the heterodyne transmitter generates +12.5dBm of output power at 77GHz, with a bandwidth of 2.5GHz leading to a four-element EIRP of 24.5dBm. Each on-chip PA has a maximum saturated power of +17.5dBm at 77GHz while the on-chip VCO achieves a phase noise of -95dBc/Hz@1MHz offset at 54GHz. The phased-array performance is measured using an internal test option and achieves 12dB peak-to-null ratio with two transmit and receive elements active.
\r\n\r\nWhile the 24GHz and 77GHz array are multiple-input single-output systems, higher-order phase-shifting and combining techniques can be used to achieve arrays with multiple outputs, with beams focused on different directions concurrently. Toward this end, a 60GHz bidirectional RF-combined phased array front-end is implemented in SiGe BiCMOS, using a hybrid parallel/series phase-shift approach that reduces the requirements of the on-chip phase shifters, enabling RF signal combining. The four-element array enables simultaneous illumination of two angles of incidence and includes amplitude control, as well as continuous phase adjustment. The front-end has a noise figure lower than 6.9dB at 60GHz and the array achieves full spatial coverage with peak-to-null ratio higher than 25dB. The four-element front-end consumes 265mW and occupies 4.6mm2 of die area.
", "doi": "10.7907/SGZC-FD54", "publication_date": "2007", "thesis_type": "phd", "thesis_year": "2007" }, { "id": "thesis:1516", "collection": "thesis", "collection_id": "1516", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-04262007-131214", "primary_object_url": { "basename": "basset-thesis.pdf", "content": "final", "filesize": 2106825, "license": "other", "mime_type": "application/pdf", "url": "/1516/1/basset-thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "CMOS Imaging Technology with Embedded Early Image Processing", "author": [ { "family_name": "Basset", "given_name": "Christophe Jean-Michel", "clpid": "Basset-Christophe-Jean-Michel" } ], "thesis_advisor": [ { "family_name": "Perona", "given_name": "Pietro", "orcid": "0000-0002-7583-5809", "clpid": "Perona-P" } ], "thesis_committee": [ { "family_name": "Perona", "given_name": "Pietro", "orcid": "0000-0002-7583-5809", "clpid": "Perona-P" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Pain", "given_name": "Bedabrata", "clpid": "Pain-B" }, { "family_name": "Mathur", "given_name": "Bimal", "clpid": "Mathur-B" }, { "family_name": "Koch", "given_name": "Christof", "orcid": "0000-0001-6482-8067", "clpid": "Koch-C" }, { "family_name": "Martin", "given_name": "Alain J.", "clpid": "Martin-A-J" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "As imaging technology evolves, so does the need for accurate, low-power and high-data-rate low-level image processing in a variety of computationally intensive vision applications. These applications include optical-flow computation, autonomous navigation, object avoidance or intercept, real-time target tracking, and recognition. To reach this goal, a single chip was developed, which functions as a camera able to preprocess the image in real time. It processes images through a convolution filter with a user-chosen kernel.
\r\n\r\nOne of the particulars of this project is to combine the processing unit with an active pixel sensors (APS) pixel array. This complementary metal-oxide semiconductor (CMOS) technology for building imager chips allows on-focal plane signal processing, as opposed to their charge-coupled device (CCD) counterparts that need to serially output the flow of pixels to an external processing chip. The filtering can therefore be implemented as a fast, low-power analog circuit.
\r\n\r\nConvolution is achieved by matching a kernel to an image using a computation unit. The chip has an integrated imager array and a digital memory large enough to store a generic, up-loadable kernel. When recognizing or tracking a target, the uploaded kernel represents the template. Other convolution filters are implemented by setting the kernel to the set of parameters corresponding to the desired task. Filtering is performed through a column-parallel architecture of computing units, so real time computation can be achieved.
\r\n\r\nSeveral versions of the convolution circuit are investigated. They have been fabricated, fully tested and characterized. A number of important design changes have occurred, either to address issues that could be improved on or to experiment with alternative approaches. Timed and geometrical amplifier controls have also been investigated. By implementing image arrays of different sizes, we also demonstrate the scalability of the architecture in the spatial domain to an arbitrarily sized imager. Test results show the analog convolution chip is a viable solution for highly integrated embedded early image processing.
", "doi": "10.7907/2GZN-T836", "publication_date": "2007", "thesis_type": "phd", "thesis_year": "2007" }, { "id": "thesis:3011", "collection": "thesis", "collection_id": "3011", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-08042006-144107", "primary_object_url": { "basename": "Thesis_Ehsan.pdf", "content": "final", "filesize": 30587538, "license": "other", "mime_type": "application/pdf", "url": "/3011/1/Thesis_Ehsan.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Optotronics: Optically Inspired Electronics", "author": [ { "family_name": "Afshari", "given_name": "Ehsan", "orcid": "0000-0002-4528-1788", "clpid": "Afshari-Ehsan" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Psaltis", "given_name": "Demetri", "clpid": "Psaltis-D" }, { "family_name": "Marsden", "given_name": "Jerrold E.", "clpid": "Marsden-J-E" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Waves are everywhere, from the distribution of cars on a highway to the wave patterns in the ocean. Intriguing phenomena in wave propagation, such as Soliton resonance, kink-antikink interaction, self-focusing, and Peakon generation can be used in many practical applications leading to novel architectures for signal processing and generation. These E/M based approaches could be particularly useful in the case of Extremely Wide Band (EWB) (DC to more than 100GHz) circuits and systems where the limited transistor cut-off frequency, maximum power efficiency, and breakdown voltage pose serious constraints on the use of conventional circuit techniques.
\r\n\r\nTo overcome the limitations of active devices in EWB signal processing and generation, we propose a general class of solutions based on novel circuit topologies inspired by commonly used structures in electromagnetics, and more specifically optics. The proposed methodology is based on nonlinear and/or inhomogeneous one-dimensional (1D) transmission lines which we have successfully extended to two-dimensional transmission lattices. The principles behind these designs stem from the mathematical theory of linear and nonlinear wave propagation. By analyzing the models for the transmission lines/lattices, we are able to exploit the large body of theory to design circuits, demonstrating the narrowest reported pulse on silicon (2.5ps), and for a single integrated-circuit silicon-based amplifier, the highest achieved center frequency of operation (85GHz) and the highest achieved power output (120mW) at this frequency. In addition, we have reported the first in-silicon transmission line system capable of sharpening both rising and falling edges of NRZ data by increasing the bandwidth. In the end, we will also present how the same approach can be applied to realize ultra-fast computation systems (such as a sub-nanosecond Fourier and Hankel transformers in silicon) and other structures, leading to a new design discipline we like to call \"Optotronics\".
\r\n", "doi": "10.7907/Z95M63XK", "publication_date": "2007", "thesis_type": "phd", "thesis_year": "2007" }, { "id": "thesis:2203", "collection": "thesis", "collection_id": "2203", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05282007-203227", "primary_object_url": { "basename": "Thesis_Komijani.pdf", "content": "final", "filesize": 9579874, "license": "other", "mime_type": "application/pdf", "url": "/2203/1/Thesis_Komijani.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Microwave Integrated Phased-Array Transmitters in Silicon", "author": [ { "family_name": "Komijani", "given_name": "Abbas", "clpid": "Komijani-Abbas" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" }, { "family_name": "Bruck", "given_name": "Jehoshua", "clpid": "Bruck-J" }, { "family_name": "D'Addario", "given_name": "Larry R.", "clpid": "D'Addario-L-R" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Phased-array systems, a special case of multiple-input-multiple-output (MIMO) systems, take advantage of spatial directivity and array gain to increase spectral efficiency. Implementing a phased-array system at high frequency in a commercial silicon process technology presents several challenges. This thesis focuses on the architectural and circuit-level trade-offs involved in the design of the silicon-based fully integrated phased-array transmitters.
\r\n \r\nAs the first implementation, a four-element 24GHz 0.18\u00b5m CMOS phased-array transmitter with integrated power amplifiers is presented. On-chip power amplifiers use substrate-shielded slow-wave transmission lines for impedance matching and can generate up to 14dBm of output power. The transmitter employs a two-step upconversion architecture with 4.8GHz as the intermediate frequency (IF) and uses a single 19.2GHz synthesizer serving as the local oscillator (LO) generator. The phased-array, employing the LO phase shifting architecture, achieves 23dB of peak to null-ratio when all four elements are used, demonstrates a beam steering range covering all signal incident angles, and can support a data rate of 500Mbps with a quadrature phase-shift keying (QPSK) baseband signal.
\r\n\r\nAs the second implementation with a modified phase shifting architecture, an integrated 4-element 77GHz Silicon-Germanium (SiGe) phased-array transceiver is presented. Two-step conversion, envisioning a dual-mode 77GHz/24GHz operation, is used at both the receiver and the transmitter paths. A differential phase of 52GHz is generated by the on-chip voltage-controlled oscillator (VCO) and is distributed to all radio frequency (RF) paths. The phase shifting is performed at the LO ports of the RF mixers with continuous analog phase shifters. The quadrature signal of the second LO, at the IF frequency of 26GHz, is generated by dividing the VCO frequency by a factor of 2 using a cross-coupled injection-locked frequency divider. The on-chip 77GHz power amplifier with an output power of 17.5dBm and peak power added efficiency (PAE) of 14% achieves the best performance demonstrated in silicon. A single transmitter path achieves a 40dB conversion gain at 77GHz with 2.5GHz of bandwidth and a maximum output power of 12.5 dBm.
\r\n\r\nThe measured results demonstrate the feasibility of using silicon-based integrated phased-arrays for wireless communication and vehicular radar applications.
", "doi": "10.7907/EW67-RX66", "publication_date": "2007", "thesis_type": "phd", "thesis_year": "2007" }, { "id": "thesis:407", "collection": "thesis", "collection_id": "407", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-01302006-154842", "primary_object_url": { "basename": "Buckwalter_Thesis01_06.pdf", "content": "final", "filesize": 8288834, "license": "other", "mime_type": "application/pdf", "url": "/407/1/Buckwalter_Thesis01_06.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Deterministic Jitter in Broadband Communication", "author": [ { "family_name": "Buckwalter", "given_name": "James Franklin", "orcid": "0000-0002-9390-0897", "clpid": "Buckwalter-James-Franklin" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Soyuer", "given_name": "Mehmet", "clpid": "Soyuer-M" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The past decade has witnessed a drastic change in the design of high-speed serial links. While Silicon fabrication technology has produced smaller, faster transistors, transmission line interconnects between chips and through backplanes have not substantially improved and have a practical bandwidth of around 3GHz. As serial link speeds increase, new techniques must be introduced to overcome the bandwidth limitation and maintain digital signal integrity. This thesis studies timing issues pertaining to bandwidth-limited interconnects. Jitter is defined as the timing uncertainty at a threshold used to detect the digital signal. Reliable digital communication requires minimizing jitter.
\r\n\r\nThe analysis and modeling presented here focuses on two types of deterministic jitter. First, dispersion of the digital signal in a bandwidth-limited channel creates data-dependent jitter. Our analysis links data sequences to unique timing deviations through the channel response and is shown for general linear time-invariant systems. A Markov model is constructed to study the impact of jitter on the operation of the serial link and provide insight in circuit performance. Second, an analysis of bounded-uncorrected jitter resulting from crosstalk induced in parallel serial links is presented.
\r\n\r\nTiming equalization is introduced to improve the signal integrity of high-speed links. The analysis of deterministic jitter leads to novel techniques for compensating the timing ambiguity in the received data. Data-dependent jitter equalization is discussed at both the receiver, where it complements the operation of clock and data recovery circuits, and as a phase pre-emphasis technique. Crosstalk-induced, bounded-uncorrected jitter can also be compensated. By detecting electromagnetic modes between neighboring serial links, a transmitter or receiver anticipates the timing deviation that has occurred along the transmission line.
\r\n\r\nFinally, we discuss a new circuit technique for submillimeter integrated circuits. Demands of wireless communication and the high speed of Silicon Germanium transistors provide opportunities for unique radio architectures for submillimeter integrated circuits. Scalable, fully-integrated phased arrays control a radiated beam pattern electronically through tiling multiple chips. Coupled-oscillator arrays are used for the first time to subharmonically injection-lock across a chip or between multiple chips to provide phase coherence across an array.
", "doi": "10.7907/EGRD-TZ84", "publication_date": "2006", "thesis_type": "phd", "thesis_year": "2006" }, { "id": "thesis:3062", "collection": "thesis", "collection_id": "3062", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-08092005-100809", "primary_object_url": { "basename": "Final_Thesis.pdf", "content": "final", "filesize": 7751861, "license": "other", "mime_type": "application/pdf", "url": "/3062/1/Final_Thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Signal Integrity Issues in High-Speed Wireline Links: Analysis and Integrated System Solutions", "author": [ { "family_name": "Analui", "given_name": "Behnam", "clpid": "Analui-Behnam" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Bruck", "given_name": "Jehoshua", "clpid": "Bruck-J" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Tai", "given_name": "Yu-Chong", "clpid": "Tai-Yu-Chong" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "This work focuses on the basic signal integrity issues of high-speed wireline links. It bridges the gap between optimum system design and circuit design for such links by: (1) understanding the effects of the system parameters on the bit error rate (BER), (2) introducing circuit architectures for the realization of systems that minimize the BER, and (3) demonstrating integrated circuit prototypes that verify the solutions.
\r\n\r\nFirst, we develop a theory that analytically relates the data link BER to the system characteristics, e.g., the channel response, the pre-amplifier bandwidth, and the transmitter clock jitter. We generate the BER contours to find the optimum receiver bandwidth as well as the optimum sampling point and its associated timing margin. We also develop the theory of the data-dependent jitter (DDJ), which is a significant component of the timing jitter in high-speed links. We provide an analytical distribution function for the DDJ of an arbitrary linear time-invariant system and include the impact of the DDJ on the BER.
\r\n\r\nSecond, we propose a bandwidth enhancement method for wideband amplifiers. This is useful for the realization of high-speed links in technologies that suffer from large parasitic components. The method leverages two-port broadband matching to enable amplifier stages to achieve their maximum gain-bandwidth product. We demonstrate a 10Gb/s CMOS 0.18um amplifier with this technique that has 2.4 times the bandwidth improvement over a design that does not apply the technique.
\r\n\r\nThird, we develop an eye-opening monitor (EOM) that enables full integration of adaptive equalizers. The EOM evaluates the signal eye diagram quality and reports a quantitative measure, which is correlated to the signal integrity. We demonstrate a prototype in 0.13um standard CMOS that operates up to 12.5Gb/s and has 68dB error dynamic range.
\r\n\r\nFinally, we introduce an instantaneous clockless demultiplexer for burst-mode communication applications. We propose a clockless finite state machine that recovers and demultiplexes the received burst of data instantaneously. The architecture consists of a combinational logic structure and a bit-period-delayed feedback loop. We demonstrate a 1:2 clockless demultiplexer based on this concept in SiGe BiCMOS technology that operates at 7.5Gb/s.
", "doi": "10.7907/GGMB-0J23", "publication_date": "2006", "thesis_type": "phd", "thesis_year": "2006" }, { "id": "thesis:3834", "collection": "thesis", "collection_id": "3834", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09302005-024349", "primary_object_url": { "basename": "thesis_xiang_final.pdf", "content": "final", "filesize": 3505176, "license": "other", "mime_type": "application/pdf", "url": "/3834/1/thesis_xiang_final.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Microwave Integrated Phased Array Receivers in Silicon", "author": [ { "family_name": "Guan", "given_name": "Xiang", "clpid": "Guan-Xiang" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Yang", "given_name": "Changhuei", "clpid": "Yang-Changhuei" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "D'Addario", "given_name": "Larry R.", "clpid": "D'Addario-L-R" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Microwave integrated systems in silicon provide a low cost, low power and high yield solution for wideband data communication, radar, and many other applications. Phased-array systems are capable of steering the radiation beam by electronic means, emulating the behavior of a directional antenna. This dissertation is dedicated to presenting various techniques to implement microwave integrated phased-array receivers in silicon-based technologies in the context of three design examples.
\r\n\r\nA 24-GHz 0.18-\u00b5m complementary metal oxide semiconductor (CMOS) front-end was demonstrated. The front-end consists of a low noise amplifier (LNA) and a mixer. The LNA utilizes a novel topology common-gate with resistive feedthrough to obtain low-noise performance. The entire front-end achieves a 7.7dB noise figure and a 27.5dB power gain.
\r\n\r\nA fully integrated 8-element 24-GHz silicon germanium (SiGe) phased array receiver was implemented. The receiver uses two-step downconversion and local oscillator (LO) phase shifting with 4-bit resolution. The signal is combined at the 4.8-GHz intermediate frequency. The 16 phases of 19.2-GHz LO signal are generated with a voltage controlled oscillator (VCO) and symmetrically distributed to the phase selectors at all path. Appropriate phase sequence is applied to the phase distribution transmission lines to minimize mismatch. An integrated frequency synthesizer locks the 19.2-GHz VCO output to a 75-MHz external reference. Measured array patterns show a peak-to-null ratio of more than 20dB and a beam steering range covering all signal incident angles.
\r\n\r\nAn integrated 4-element 77-GHz SiGe wideband phased-array transceiver was implemented. Two-step conversion is used at both the receiver and the transmitter. A differential phase of 52 GHz is generated by the VCO and distributed to all RF paths at the transmitter and receiver. The phase shifting is performed at the LO ports of the RF mixers using continuous analog phase shifters. The quadrature signal of the second LO frequency is generated by dividing the VCO frequency by a factor of 2 using a cross-coupled injection-locked frequency divider. The signal combining is performed at IF with an active combining amplifier. The receiver achieves a 41dB gain at 80 GHz with 3 GHz of bandwidth. The 52-GHz-to-50MHz frequency divider chain obtains 7% locking range.
", "doi": "10.7907/E5GE-EP91", "publication_date": "2006", "thesis_type": "phd", "thesis_year": "2006" }, { "id": "thesis:1098", "collection": "thesis", "collection_id": "1098", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-03242006-132815", "primary_object_url": { "basename": "Thesis(sanggeun)_final.pdf", "content": "final", "filesize": 3073399, "license": "other", "mime_type": "application/pdf", "url": "/1098/1/Thesis(sanggeun)_final.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Design and Stability Analysis Techniques for Switching-Mode Nonlinear Circuits: Power Amplifiers and Oscillators", "author": [ { "family_name": "Jeon", "given_name": "Sanggeun", "orcid": "0000-0001-7453-2331", "clpid": "Jeon-Sanggeun" } ], "thesis_advisor": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" } ], "thesis_committee": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Stancil", "given_name": "Daniel D.", "clpid": "Stancil-D-D" }, { "family_name": "Doyle", "given_name": "John Comstock", "clpid": "Doyle-J-C" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "A design technique for kW level switching mode power amplifiers is presented. Several push pull pairs, independently tuned to Class E/Fodd, are combined by a distributed active transformer. The zero voltage switching (ZVS) condition is investigated and modified for the Class-E/Fodd amplifier with a non-ideal output transformer. All lumped elements including the DAT, the transistor package, and the input power distribution network are modeled and optimized to achieve the ZVS condition and the high drain efficiency. Two power amplifiers are implemented at 29 MHz, following the technique. The amplifier with two push pull pairs combined exhibits 1.5 kW output power with 85 % drain efficiency and 18 dB gain. When four push pull pairs are combined, an output power of 2.7 kW is achieved with 79 % drain efficiency and 18 dB gain.
\r\n\r\nNonlinear stability analysis techniques, based on an auxiliary generator and pole zero identification, are introduced to predict and eliminate the instabilities of power amplifiers. The techniques are applied to two switching mode power amplifiers that exhibited different instabilities during the measurements. Self-oscillation, chaos, and hysteresis of a Class E/Fodd amplifier with a distributed active transformer are investigated by the stability and bifurcation analysis tools. An in-depth analysis of the oscillation mechanism is also carried out, which enables an efficient determination of the topology and location of the required global stabilization network. As the other application, the anomalous behavior observed in a Class-E power amplifier is analyzed in detail. It involves hysteresis in the power-transfer curve, self oscillation, harmonic synchronization, and noisy precursors. To correct the amplifier performance, a new technique for elimination of the hysteresis is proposed, based on bifurcation detection through a single simulation on harmonic-balance software. Also, investigated are the circuit characteristics that make the noisy precursors observable in practical circuits and a technique is derived for their elimination from the amplifier output spectrum. All of the stabilization and correction of the amplifiers are experimentally validated.
\r\n\r\nA simple nonlinear technique for the design of high efficiency and high-power switching-mode oscillators is presented. It combines existing quasi-nonlinear methods and the use of an auxiliary generator in harmonic balance. The auxiliary generator enables the oscillator optimization to achieve high output power and dc to rf conversion efficiency without affecting the oscillation frequency. It also imposes a sufficient drive on the transistor to enable the switching mode operation with high efficiency. The oscillation start-up condition and the steady state stability are analyzed with the pole-zero identification technique. The influence of the gate bias on the output power, efficiency, and stability is also investigated. A Class E oscillator is demonstrated using the proposed technique. The oscillator exhibits 75 W with 67 % efficiency at 410 MHz.
", "doi": "10.7907/V4YT-YM88", "publication_date": "2006", "thesis_type": "phd", "thesis_year": "2006" }, { "id": "thesis:2056", "collection": "thesis", "collection_id": "2056", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05252006-145119", "primary_object_url": { "basename": "ania_thesis.pdf", "content": "final", "filesize": 1730495, "license": "other", "mime_type": "application/pdf", "url": "/2056/1/ania_thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "A Compact System for Self-Motion Estimation", "author": [ { "family_name": "Mitros", "given_name": "Ania Karolina", "clpid": "Mitros-Ania-Karolina" } ], "thesis_advisor": [ { "family_name": "Koch", "given_name": "Christof", "orcid": "0000-0001-6482-8067", "clpid": "Koch-C" }, { "family_name": "Diorio", "given_name": "Christopher J.", "clpid": "Diorio-Christopher-J" } ], "thesis_committee": [ { "family_name": "Koch", "given_name": "Christof", "orcid": "0000-0001-6482-8067", "clpid": "Koch-C" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Diorio", "given_name": "Christopher J.", "clpid": "Diorio-Christopher-J" }, { "family_name": "Burdick", "given_name": "Joel Wakeman", "orcid": "0000-0002-3091-540X", "clpid": "Burdick-J-W" }, { "family_name": "Perona", "given_name": "Pietro", "orcid": "0000-0002-7583-5809", "clpid": "Perona-P" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Self-motion estimation is a vital problem for autonomous robots, frequently and appropriately addressed by vision algorithms. Most approaches involve repeating some local calculation over the entire imaging array, such as detection of locally salient features. A simple and local calculation can be efficiently implemented on the same chip as the photo-sensing array, thus parallelizing a huge computational task and vastly reducing the amount of data to transmit off chip. Mismatch between devices has previously been a stumbling block to producing truly useful arrays of local processing elements. Floating gate technology is used here as a compact means of programming away offsets in subcircuits to remedy this problem. A custom analog chip performs the above functions. For each pixel, the chip outputs sensed light intensity, the values of the vertical and horizontal intensity gradients, and a binary value indicating whether a feature is centered on that pixel. These values can be used as inputs to a motion estimation algorithm implemented on a standard computer.", "doi": "10.7907/50B3-RW79", "publication_date": "2006", "thesis_type": "phd", "thesis_year": "2006" }, { "id": "thesis:5219", "collection": "thesis", "collection_id": "5219", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06012005-091623", "primary_object_url": { "basename": "Gunn_Thesis_20050523.pdf", "content": "final", "filesize": 9658401, "license": "other", "mime_type": "application/pdf", "url": "/5219/1/Gunn_Thesis_20050523.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Integration of Complex Optical Functionality in a Production CMOS Process", "author": [ { "family_name": "Gunn", "given_name": "Lawrence Cary, III", "clpid": "Gunn-Lawrence-Cary-III" } ], "thesis_advisor": [ { "family_name": "Scherer", "given_name": "Axel", "clpid": "Scherer-A" } ], "thesis_committee": [ { "family_name": "Scherer", "given_name": "Axel", "clpid": "Scherer-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Psaltis", "given_name": "Demetri", "clpid": "Psaltis-D" }, { "family_name": "Yablonovitch", "given_name": "Eli", "clpid": "Yablonovitch-E" }, { "family_name": "Bridges", "given_name": "William B.", "clpid": "Bridges-W-B" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Optical functionality has been developed within the confines of an existing CMOS process. As of this writing, 10Gigabit modulators, electrically tunable optical filters, waveguides, and grating coupler technology have been successfully implemented alongside the existing transistors in the Freescale Hip7SOI process. This technology will be used to manufacture high bandwidth optical interconnections directly on silicon chips, allowing a new type of network and computing infrastructure to be developed.
\r\n\r\nThis work is covered in two distinct phases. First, the exploratory work done to gain experience with high index contrast silicon waveguides primarily served to uncover challenges related with simulation of these devices, and with the practical limitations of efficiently coupling the resulting waveguide devices with the outside world.
\r\n\r\nThe second phase began as the grating coupler emerged to address the coupling challenge. It became feasible to conceive of a commercially viable technology based on silicon photonics. The coupler has been evolved to a high level, currently achieving coupling loss of less than 1dB. Once the light is on chip, filtering and modulation technology are implemented. The reverse-biased plasma dispersion modulator has a 3dB roll-off of 10GHz, and an insertion loss less than 5dB. Optical filters based on ring resonators, arrayed waveguide gratings, and interleavers have all been implemented, often with world record performance, and many of the devices have been made electronically tunable to compensate for manufacturing variations and environmental excursions.
\r\n\r\nFinally, circuitry has been designed and constructed on the same die with the optical functionality, fully demonstrating the ability to achieve monolithic integration of these devices.
", "doi": "10.7907/HKW9-4K53", "publication_date": "2005", "thesis_type": "phd", "thesis_year": "2005" }, { "id": "thesis:2332", "collection": "thesis", "collection_id": "2332", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05312005-225644", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 2726540, "license": "other", "mime_type": "application/pdf", "url": "/2332/1/thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Linearized and High Frequency Electrooptic Modulators", "author": [ { "family_name": "Cummings", "given_name": "Uri Vaughan", "clpid": "Cummings-Uri-Vaughan" } ], "thesis_advisor": [ { "family_name": "Bridges", "given_name": "William B.", "clpid": "Bridges-W-B" } ], "thesis_committee": [ { "family_name": "Bridges", "given_name": "William B.", "clpid": "Bridges-W-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Schaffner", "given_name": "James H.", "clpid": "Schaffner-J-H" }, { "family_name": "Vaidyanathan", "given_name": "P. P.", "clpid": "Vaidyanathan-P-P" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "An analysis is performed of many standard and linearized electrooptic modulators known in the industry. The transfer functions of these modulators are evaluated under a consistent set of performance figures of merit, which are gain and spur-free dynamic range, using a canonical set of optical link parameters. The tolerance of the needed precision of the parameters of the linearization mechanisms of all of these modulators is compared over the entire interesting range of noise bandwidth.
\r\n\r\nA computer program was written to analyze the frequency dependence of any modulator transfer function under any set of functional inputs. The program is used to illustrate and compare the frequency dependence of the figures of merit of all of the modulators for which a d-c analysis was performed. Further analysis looks at the effect of greater noise-bandwidth and recovering the frequency-dependent degradation of gain and dynamic range through re-phasing techniques. The gain of directional couplers is analyzed in-depth.
\r\n\r\nTwo novel modulator schemes are produced. The first uses reflective wave techniques to retime the electrical and optical waves half way through the modulator. The second uses fabrication geometry and properties of the linearization technique to make a more robust modulator (applicable to three of the modulators analyzed).
\r\n\r\nA 94 GHz antenna-coupled directional coupler modulator was initially demonstrated using an old modulator chip from Finbar Sheehy. A peculiar bug with the chip was uncovered. And a new modulator experiment was constructed and many aspects of the experimental apparatus were optimized. Though the revised experiment ultimately did not yield modulation side bands, it did couple a 94 GHz microwave signal into the optical waveguide, and many interesting challenges of high frequency electrooptic modulator fabrication were evaluated and improved upon.
", "doi": "10.7907/GTD7-V873", "publication_date": "2005", "thesis_type": "phd", "thesis_year": "2005" }, { "id": "thesis:2818", "collection": "thesis", "collection_id": "2818", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-07072004-154316", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 2283527, "license": "other", "mime_type": "application/pdf", "url": "/2818/1/thesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Interval Modulation: A New Paradigm for the Design of High Speed Communication Systems", "author": [ { "family_name": "Mukhtar", "given_name": "Saleem", "clpid": "Mukhtar-Saleem" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Bruck", "given_name": "Jehoshua", "orcid": "0000-0001-8474-0812", "clpid": "Bruck-J" }, { "family_name": "Sternberg", "given_name": "Paul W.", "orcid": "0000-0002-7699-0173", "clpid": "Sternberg-P-W" } ], "thesis_committee": [ { "family_name": "Koch", "given_name": "Christof", "orcid": "0000-0001-6482-8067", "clpid": "Koch-C" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Bruck", "given_name": "Jehoshua", "orcid": "0000-0001-8474-0812", "clpid": "Bruck-J" }, { "family_name": "McEliece", "given_name": "Robert J.", "clpid": "McEliece-R-J" }, { "family_name": "Low", "given_name": "Steven H.", "orcid": "0000-0001-6476-3048", "clpid": "Low-S-H" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "In this thesis we propose a new, biologically inspired, paradigm for the design of high speed communication systems. The paradigm consists of a new modulation format referred to as Interval Modulation (IM). In order to transmit data in an efficient manner using this format, new coding techniques are needed. In this thesis we propose a coding technique based on variable length to variable length prefix trees and code construction algorithms are outlined. These codes are referred to as Interval Modulation Codes (IMC). Furthermore, data encoded with this modulation format cannot be transmitted or received using conventional synchronous CDR based receivers. In this thesis we outline a new asynchronous circuit architecture for both the transmitter and receiver. The architecture is based on active delay lines and eliminates the need for clock recovery.", "doi": "10.7907/6F03-MP11", "publication_date": "2005", "thesis_type": "phd", "thesis_year": "2005" }, { "id": "thesis:2089", "collection": "thesis", "collection_id": "2089", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05262005-100534", "primary_object_url": { "basename": "BhatThesis_05_26_2005.pdf", "content": "final", "filesize": 1917954, "license": "other", "mime_type": "application/pdf", "url": "/2089/1/BhatThesis_05_26_2005.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Lagrangian Averaging, Nonlinear Waves, and Shock Regularization", "author": [ { "family_name": "Bhat", "given_name": "Harish Subrahmanya", "orcid": "0000-0001-7631-1831", "clpid": "Bhat-Harish-Subrahmanya" } ], "thesis_advisor": [ { "family_name": "Marsden", "given_name": "Jerrold E.", "clpid": "Marsden-J-E" } ], "thesis_committee": [ { "family_name": "Marsden", "given_name": "Jerrold E.", "clpid": "Marsden-J-E" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Fetecau", "given_name": "Razvan Constantin", "clpid": "Fetecau-R-C" }, { "family_name": "Murray", "given_name": "Richard M.", "clpid": "Murray-R-M" }, { "family_name": "Schneider", "given_name": "Tapio", "clpid": "Schneider-T" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "In this thesis, we explore various models for the flow of a compressible fluid as well as model equations for shock formation, one of the main features of compressible fluid flows.
\r\n\r\nWe begin by reviewing the variational structure of compressible fluid mechanics. We derive the barotropic compressible Euler equations from a variational principle in both material and spatial frames. Writing the resulting equations of motion requires certain Lie-algebraic calculations that we carry out in detail for expository purposes.
\r\n\r\nNext, we extend the derivation of the Lagrangian averaged Euler (LAE-alpha) equations to the case of barotropic compressible flows. The derivation in this thesis involves averaging over a tube of trajectories centered around a given Lagrangian flow. With this tube framework, the LAE-alpha equations are derived by following a simple procedure: start with a given action, expand via Taylor series in terms of small-scale fluid fluctuations, truncate, average, and then model those terms that are nonlinear functions of the fluctuations.
\r\n\r\nWe then analyze a one-dimensional subcase of the general models derived above. We prove the existence of a large family of traveling wave solutions. Computing the dispersion relation for this model, we find it is nonlinear, implying that the equation is dispersive. We carry out numerical experiments that show that the model possesses smooth, bounded solutions that display interesting pattern formation.
\r\n\r\nFinally, we examine a Hamiltonian partial differential equation (PDE) that regularizes the inviscid Burgers equation without the addition of standard viscosity. Here alpha is a small parameter that controls a nonlinear smoothing term that we have added to the inviscid Burgers equation. We show the existence of a large family of traveling front solutions. We analyze the initial-value problem and prove well-posedness for a certain class of initial data. We prove that in the zero-alpha limit, without any standard viscosity, solutions of the PDE converge strongly to weak solutions of the inviscid Burgers equation. We provide numerical evidence that this limit satisfies an entropy inequality for the inviscid Burgers equation. We demonstrate a Hamiltonian structure for the PDE.
", "doi": "10.7907/8DJ2-F672", "publication_date": "2005", "thesis_type": "phd", "thesis_year": "2005" }, { "id": "thesis:5197", "collection": "thesis", "collection_id": "5197", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05242005-172142", "primary_object_url": { "basename": "thesis_ch1.pdf", "content": "final", "filesize": 273247, "license": "other", "mime_type": "application/pdf", "url": "/5197/1/thesis_ch1.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "A Solid-state Atomic Frequency Standard", "author": [ { "family_name": "White", "given_name": "Christopher John", "clpid": "White-Christopher-John" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Weitekamp", "given_name": "Daniel P.", "clpid": "Weitekamp-D-P" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Roukes", "given_name": "Michael Lee", "clpid": "Roukes-M-L" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Bridges", "given_name": "William B.", "clpid": "Bridges-W-B" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The thesis describes a new class of frequency reference. The frequency source uses the same operating principle as a passive atomic frequency standard; however, the device is entirely solid-state, removing many cost and reliability issues associated with gas-phase atomic clocks. More specifically, the \"atomic resonance\" is derived from zero-field magnetic resonance transitions of the vanadium ion in a cubic crystal lattice. The characteristics of these resonances will be described in detail. The apparatus for measuring the \"atomic\" resonances uses a radio-frequency resonant cavity and frequency discriminator circuit. Using integrated circuits, the radio-frequency signal processing functions can be implemented at very low cost in a reliable manufacturing process. We discuss the system design and the measurement sensitivity. Advantages of the new frequency reference may include immunity to vibration and reduced aging compared to crystal oscillators.", "doi": "10.7907/ATKE-YX40", "publication_date": "2005", "thesis_type": "phd", "thesis_year": "2005" }, { "id": "thesis:1591", "collection": "thesis", "collection_id": "1591", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05032004-153842", "primary_object_url": { "basename": "marc.riedel.phd.pdf", "content": "final", "filesize": 2195990, "license": "other", "mime_type": "application/pdf", "url": "/1591/1/marc.riedel.phd.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Cyclic Combinational Circuits", "author": [ { "family_name": "Riedel", "given_name": "Marcus D.", "orcid": "0000-0002-3318-346X", "clpid": "Riedel-Marcus-D" } ], "thesis_advisor": [ { "family_name": "Bruck", "given_name": "Jehoshua", "clpid": "Bruck-J" } ], "thesis_committee": [ { "family_name": "Bruck", "given_name": "Jehoshua", "clpid": "Bruck-J" }, { "family_name": "Martin", "given_name": "Alain J.", "clpid": "Martin-A-J" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Viterbi", "given_name": "Andrew", "clpid": "Viterbi-A" }, { "family_name": "Winfree", "given_name": "Erik", "clpid": "Winfree-E" }, { "family_name": "Abu-Mostafa", "given_name": "Yaser S.", "clpid": "Abu-Mostafa-Y-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "A collection of logic gates forms a combinational circuit if the outputs can be described as Boolean functions of the current input values only. Optimizing combinational circuitry, for instance, by reducing the number of gates (the area) or by reducing the length of the signal paths (the delay), is an overriding concern in the design of digital integrated circuits.
\r\n\r\nThe accepted wisdom is that combinational circuits must have acyclic (i.e., loop-free or feed-forward) topologies. In fact, the idea that \"combinational\" and \"acyclic\" are synonymous terms is so thoroughly ingrained that many textbooks provide the latter as a definition of the former. And yet simple examples suggest that this is incorrect. In this dissertation, we advocate the design of cyclic combinational circuits (i.e., circuits with loops or feedback paths). We demonstrate that circuits can be optimized effectively for area and for delay by introducing cycles.
\r\n\r\nOn the theoretical front, we discuss lower bounds and we show that certain cyclic circuits are one-half the size of the best possible equivalent acyclic implementations. On the practical front, we describe an efficient approach for analyzing cyclic circuits, and we provide a general framework for synthesizing such circuits. On trials with industry-accepted benchmark circuits, we obtained significant improvements in area and delay in nearly all cases. Based on these results, we suggest that it is time to re-write the definition: combinational might well mean cyclic.
", "doi": "10.7907/410B-XR25", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:2455", "collection": "thesis", "collection_id": "2455", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-06052004-180113", "primary_object_url": { "basename": "FinalThesis.pdf", "content": "final", "filesize": 5372636, "license": "other", "mime_type": "application/pdf", "url": "/2455/1/FinalThesis.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Frequency Generation Techniques for Integrated Applications", "author": [ { "family_name": "Aparicio Joo", "given_name": "Roberto", "orcid": "0000-0003-2910-9969", "clpid": "Aparicio-Joo-Roberto" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Tai", "given_name": "Yu-Chong", "clpid": "Tai-Yu-Chong" }, { "family_name": "Bruck", "given_name": "Jehoshua", "clpid": "Bruck-J" }, { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "This thesis presents novel oscillator topologies and passive structures that demonstrate improvements in performance compared to existing devices in CMOS. The contributions of this work include the development of original topologies and concepts together with practical implications in the area of integrated frequency generation.
\r\n\r\nA noise-shifting differential Colpitts oscillator topology is proposed. It is less sensitive to noise generated by the active devices than commonly used integrated oscillator topologies such as NMOS- or PMOS-only, and complementary cross-coupled. This is achieved through cyclostationary noise alignment while providing a fully differential output and large loop gain for reliable start up. An optimization strategy is derived for this oscillator that is used in the implementation of a CMOS prototype. The performance of this oscillator is compared to traditional topologies and previously published integrated oscillators achieving lower phase noise and some of the highest figures of merit, respectively.
\r\n\r\nA new circular-geometry oscillator topology is introduced. It allows the implementation of slab inductors for high-frequency and low-phase noise oscillator applications. Slab inductors present an attractive alternative for monolitic applications where low loss, low impedance, and high self-resonance integrated inductors are required. A general methodology to ensure the proper oscillation mode when several oscillator cores are coupled in a circular-geometry as well as to achieve a stable dc bias point is offered. Several circular-geometry CMOS integrated oscillator prototypes are presented as a proof of concept and their performances are compared to previously published high frequency oscillators achieving some of the best figures of merit.
\r\n\r\nTheoretical limits for the capacitance density of integrated capacitors with combined lateral and vertical field components are derived. These limits are used to investigate the efficiency of various capacitive structures such as lateral flux and quasi-fractal capacitors. This study leads to two new capacitor structures with high lateral-field efficiencies. These new capacitors demonstrate larger capacities, superior matching properties, tighter tolerances, and higher self-resonance frequencies than the standard horizontal parallel plate and previously reported lateral-field capacitors, while maintaining comparable quality factors. These superior qualities are verified by simulation and experimental results.
\r\n\r\nFinally, three phase-locked-loops (PLL) are presented. A 6.6GHz PLL for applications in a concurrent dual-band CMOS receiver is described. Careful frequency planning allows the generation of the three local oscillator signals required by the entire receiver using only one PLL, reducing power consumption and chip area considerably. The design issues of an ultra-low-power PLL prototype implemented in a sub-micron CMOS process are also discussed. The design of a low-power 3.2GHz PLL implementing a phase-compensation technique for fractional-N frequency synthesis is described. It uses an on-chip delay-locked-loop tuning scheme that attenuates the fractional spur independent of the output frequency and process variations.
", "doi": "10.7907/S2EP-3A93", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:3832", "collection": "thesis", "collection_id": "3832", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09302003-125128", "primary_object_url": { "basename": "HH_ETD.pdf", "content": "final", "filesize": 2005939, "license": "other", "mime_type": "application/pdf", "url": "/3832/1/HH_ETD.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Integrated Concurrent Multi-Band Radios and Multiple-Antenna Systems", "author": [ { "family_name": "Hashemi", "given_name": "Hossein", "orcid": "0000-0002-3329-7061", "clpid": "Hashemi-Hossein" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Hassibi", "given_name": "Babak", "clpid": "Hassibi-B" }, { "family_name": "Tai", "given_name": "Yu-Chong", "clpid": "Tai-Yu-Chong" }, { "family_name": "Painter", "given_name": "Oskar J.", "clpid": "Painter-O" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "This thesis presents a unique view on radio systems that can simultaneously function at multiple frequency bands. These radios offer a higher data-rate and robustness in addition to the added functionality in the performance of wireless systems. Our treatment includes the definition of such novel radios, formulation of their singular characteristics, proposition for transceiver architectures, and invention of circuit blocks.
\r\n\r\nVarious transceiver architectures for this new class of concurrent multi-band radios are proposed. The results for an integrated concurrent dual-band receiver operating at 2.4 GHz and 5.2 GHz frequency bands for wireless networking applications are presented. Meticulous frequency-planning results in a high level of integration and a low power design for the concurrent receiver. Several new circuit concepts including the concurrent multi-band low-noise amplifier are demonstrated in this design. A general class of these concurrent multi-band amplifiers is investigated with numerous implementations of integrated concurrent dual-band and triple-band amplifiers.
\r\n\r\nA theoretical treatment of nonlinear oscillators with multi-band resonator structures is also offered. It is shown that given certain nonlinearities these oscillators can generate multi-frequency outputs. The phase-noise of such negative-resistance oscillators with general resonator structure is addressed. By providing a link between the stored and dissipated energies of a network and its associated circuit parameters, useful interpretations of resonator quality factor are derived. With the aid of this analysis and the previously developed phase-noise models, dependencies of phase-noise on the resonator structure are derived. Based on our theoretical results, enhanced resonators with higher quality factor providing a superior oscillator phase-noise are proposed.
\r\n\r\nFinally, in order to enhance the performance of wireless systems by exploiting the spatial properties of the electromagnetic wave, multiple-antenna radios in phased-array configuration are investigated. The phased-array technology results in higher immunity to unwanted interference and therefore achieves a superior overall system capacity in a shared environment. The first fully integrated multiple-antenna receiver targeting the 24 GHz ISM band using silicon technology is presented. The phased-array radio at 24 GHz is a cheap solution for high data-rate WLAN, as well as for fixed wireless broadband access applications.
", "doi": "10.7907/3R2B-8A25", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:1909", "collection": "thesis", "collection_id": "1909", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05212004-015508", "primary_object_url": { "basename": "Thesis_DaiLu.pdf", "content": "final", "filesize": 7365248, "license": "other", "mime_type": "application/pdf", "url": "/1909/1/Thesis_DaiLu.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Active Patch Array Design and Indoor Channel Modeling for Future Wireless Communications", "author": [ { "family_name": "Lu", "given_name": "Dai", "clpid": "Lu-Dai" } ], "thesis_advisor": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" } ], "thesis_committee": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Effros", "given_name": "Michelle", "clpid": "Effros-M" }, { "family_name": "Pogorzelski", "given_name": "Ronald", "clpid": "Pogorzelski-R" }, { "family_name": "Bruck", "given_name": "Jehoshua", "clpid": "Bruck-J" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Indoor wireless LAN systems currently operate at ranges of up to 30 meters, with practical data rates of 10 Mbps. In order to achieve higher data rates, higher frequencies are under consideration. Smaller antennas are required at these frequencies, but path loss increases. To combat the large path loss and multipath, 24 GHz phased arrays are being considered. The advantage of a phased array is that it can form narrow beams to favored directions, and nulls to combat interference. A 24 GHz active antenna with a 5-element patch array is demonstrated that includes an integrated GaAs MMIC power amplifier and low noise amplifier chip. Bias switching is used for changing from transmit to receive. The measured active gain is 31 dB in receive and 35 dB in transmit. The measured noise figure in receive is 3.5 dB and the maximum output power in transmit is 22 dBm (158 mW). Indoor wireless channels are investigated at five different frequency bands. The understanding of the channel will help link budgeting and system planning for future wireless communication. An automatic testing system has been developed using remote control by LABVIEW. This increases testing efficiency and reduces near field interference from the operator. A combined E/H plane 2-D ray-tracing method is proposed to predict the channel performance. This approach accurately predicts path loss for both line-of-sight and non-line-of-sight paths. It predicts the delay spread in line-of-sight paths well but fails for non-line-of-sight paths. This could be due to the ignorance of some higher order paths with small amplitudes but near random phases. In addition, a 3-D simplified ray-tracing code is developed to for access point optimization and to predict human shadow effects.\r\n", "doi": "10.7907/PVB9-TH19", "publication_date": "2004", "thesis_type": "phd", "thesis_year": "2004" }, { "id": "thesis:1867", "collection": "thesis", "collection_id": "1867", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05192003-161134", "primary_object_url": { "basename": "final_master.pdf", "content": "final", "filesize": 5040312, "license": "other", "mime_type": "application/pdf", "url": "/1867/1/final_master.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Waveguide Packaging of Quasi-Optical Grid Amplifiers", "author": [ { "family_name": "Cheung", "given_name": "Chun Tung", "clpid": "Cheung-Chun-Tung" } ], "thesis_advisor": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" } ], "thesis_committee": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Rosenberg", "given_name": "Jim", "clpid": "Rosenberg-J" }, { "family_name": "Vahala", "given_name": "Kerry J.", "clpid": "Vahala-K-J" }, { "family_name": "Bridges", "given_name": "William B.", "clpid": "Bridges-W-B" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "Quasi-optical amplifiers combining the output powers of hundreds of transistors have demonstrated the capability to deliver more than 10 Watts of power at millimeter wave frequencies. However, these amplifiers are large and expensive to manufacture. In this work, we attempt to find a compact, low-cost approach using metallic waveguide to package a grid amplifier. This thesis details the design and implementation of a grid amplifier packaged in waveguide. Frequency and time-domain simulation methods are used to calculate the field flatness and the small signal gain of the amplifier. Four different active grids packaged in waveguide will be reported. The first grid, operating at Ka-band, is fed with a waveguide and radiates its output into free space. The amplifier chip design was previously measured in free-space. This work demonstrates a small signal gain of 7 dB with output power of 5.5 W at 3-dB compression. The performance is similar to the same grid design measured in free-space. A second Ka-band grid amplifier packaged in waveguide for both input and output gives a small signal gain of 6 dB. The 3-dB compressed output power is 670 mW while the same amplifier measured in free-space gave 1.2 W output power. In order to further verify our active grid and packaging design methods, a V-band single-stage monolithic grid amplifier was designed and fabricated. A transmission grid amplifier and a reflection grid amplifier using this chip were fabricated. Both amplifiers have 2 dB small-signal gain at 58 GHz. In order to increase small-signal gain, a two-stage monolithic grid amplifier was designed and fabricated. A reflection approach was used to package this chip. Measured small-signal gain was 2.7 dB at 82 GHz.", "doi": "10.7907/KSGC-3G92", "publication_date": "2003", "thesis_type": "phd", "thesis_year": "2003" }, { "id": "thesis:2296", "collection": "thesis", "collection_id": "2296", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05302003-160130", "primary_object_url": { "basename": "Dissertation_HuiWu.pdf", "content": "final", "filesize": 2612049, "license": "other", "mime_type": "application/pdf", "url": "/2296/1/Dissertation_HuiWu.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Signal Generation and Processing in High-Frequency / High-Speed Silicon-Based Integrated Circuits", "author": [ { "family_name": "Wu", "given_name": "Hui", "clpid": "Wu-Hui" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" }, { "family_name": "Bridges", "given_name": "William B.", "clpid": "Bridges-W-B" }, { "family_name": "Tai", "given_name": "Yu-Chong", "orcid": "0000-0001-8529-106X", "clpid": "Tai-Yu-Chong" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "High-frequency/high-speed integrated circuits become increasingly important because of the strong demand for higher data rate and lower power consumption, and they rely more on silicon-based technologies, which has the advantages of low cost, fast technological development and system-on-a-chip (SoC) capabilities. However, silicon technologies also present great challenges in high-frequency/high-speed integrated circuits. This work demonstrated that distributed circuit and injection locking are two enabling circuit techniques that can help overcome silicon limitations.
\r\n\r\nDistributed voltage-controlled oscillators (DVCO's) demonstrated the high-frequency capabilities of distributed circuits. The operation of distributed oscillators is analyzed and the general oscillation condition is derived, resulting in analytical expressions for the oscillation frequency and amplitude. Two tuning techniques are developed, namely, the inherent-varactor tuning and delay-balanced current-steering tuning. A complete analysis of the tuning techniques is also presented. CMOS and bipolar DVCO prototypes have been designed and fabricated in a commercial 0.35\u00b5m BiCMOS process. A 10-GHz CMOS DVCO achieves a tuning range of 12\\% and a phase noise of -103 dBc/Hz at 600 kHz frequency offset. A 12-GHz bipolar DVCO achieves a tuning range of 26% and a phase noise of -99 dBc/Hz at 600 kHz frequency offset. New DVCO architectures are also proposed to improve the performance.
\r\n\r\nThe distributed circuit technique is also used for equalization in high-speed fiber-optic systems, in which inter-symbol interference (ISI) caused by fibre dispersion imposes a major limitation. Compared to optical-domain methods and other electrical-domain methods, equalization with distributed transversal filters (DTF's) presents the most cost-effective and SoC-compatible solution. Prototype DTF's have been implemented in a commercial 0.18\u00b5m SiGe BiCMOS process for 10 Gpbs fiber-optic systems. A 7-tap DTF reduces the ISI of a 10 Gbps signal after 800m 50\u00b5m multi-mode fiber from 5 dB to 1.38 dB, and improves the BER from 10\u207b\u2075 to 10\u207b\u00b9\u00b2.
\r\n\r\nThe injection locking technique is applied in high-speed, low-power frequency dividers, namely, injection-locked frequency dividers (ILFD's). Based on the detailed analysis, shunt-peaking and oscillation-suppression techniques are developed to enhance the locking range. Prototypes are implemented in a commercial 0.35\u00b5m BiCMOS process using only CMOS transistors. A 19 GHz ILFD achieves a locking range of 1350 MHz with the power consumption of 1 mW. A 9 GHz ILFD achieves a locking range of 1490 MHz with the power consumption of 1.3 mW. Self-dividing oscillators are proposed to generate accurate low-phase-noise quadrature signals.
", "doi": "10.7907/51YY-3Y81", "publication_date": "2003", "thesis_type": "phd", "thesis_year": "2003" }, { "id": "thesis:3564", "collection": "thesis", "collection_id": "3564", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09162005-110430", "primary_object_url": { "basename": "Pornsinsirirak_tn_2002.pdf", "content": "final", "filesize": 47885172, "license": "other", "mime_type": "application/pdf", "url": "/3564/1/Pornsinsirirak_tn_2002.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Parylene MEMS Technology for Adaptive Flow Control of Flapping Flight", "author": [ { "family_name": "Pornsinsirirak", "given_name": "Teerachai Nicholas", "clpid": "Pornsinsirirak-Teerachai-Nicholas" } ], "thesis_advisor": [ { "family_name": "Neugebauer", "given_name": "Gerry", "clpid": "Neugebauer-G" } ], "thesis_committee": [ { "family_name": "Tai", "given_name": "Yu-Chong", "orcid": "0000-0001-8529-106X", "clpid": "Tai-Yu-Chong" }, { "family_name": "Neugebauer", "given_name": "Gerry", "clpid": "Neugebauer-G" }, { "family_name": "Burdick", "given_name": "Joel Wakeman", "orcid": "0000-0002-3091-540X", "clpid": "Burdick-J-W" }, { "family_name": "Elachi", "given_name": "Charles", "clpid": "Elachi-C" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Ho", "given_name": "C-M", "clpid": "Ho-C-M" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "This thesis is the culmination of research work in developing a parylene MEMS technology to fabricate MEMS wings and large-area parylene actuator skins for real-time adaptive flow control for flapping flight applications.\r\n\r\nIn this thesis, the novel MEMS-based wing technology is presented using titanium-alloy metal (Ti-6A1-4V) as wingframe and parylene-C as wing membrane. With this technology, the ability to produce light, yet robust, 3-D wings can be achieved. The use of MEMS technology enables systematic research in terms of repeatability, size control, weight minimization, and mass production of the wings. By fabricating the wing with the photolithography and etching techniques, fast turnaround time of various wing designs can be easily obtained. The wings are optimized to utilize the flow separation to achieve a high lift coefficient, C(L), as large as five times that of the fixed-wing aircraft. The aerodynamic tests are performed in a high quality low-speed wind tunnel with velocity uniformity of 0.5% and speeds range from 1 to 10 m/s. The wind-tunnel test results are presented and discussed.\r\n\r\nAs part of the investigation to integrate MEMS actuators onto the wings for realtime adaptive flow control, the MEMS technology is developed to fabricate the first large-area wafer-sized, flexible parylene MEMS electrostatic actuator skins. The technology is first developed to fabricate parylene actuator diaphragm on a silicon chip. The actuator diaphragm is made of two metallized layers of parylene membranes with offset vent holes. Without electrostatic actuation, air can move freely from one side of the skin to the other side through the vent holes. With actuation, these vent holes are sealed and the airflow is controlled. The membrane behaves as a complete diaphragm. This function is successfully demonstrated using a 2-mm x 2-mm parylene diaphragm electrostatic actuator valves.\r\n\r\nFinally, this technology is applied to fabricate large area wafer-sized actuator skins. The skins contain only parylene and metalized electrodes and have no bulk silicon as a structural component. Plate and check-valved skin types are fabricated and both are integrated onto the MEMS wings for aerodynamic flow control. The integration of micro-valved actuators has shown significant effect on the aerodynamic performance of the flapping flight. The wind-tunnel test results are analyzed and discussed in detail in this thesis.\r\n", "doi": "10.7907/jtjd-dd33", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:967", "collection": "thesis", "collection_id": "967", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-03162005-141416", "primary_object_url": { "basename": "Ham_d_2002.pdf", "content": "final", "filesize": 8325658, "license": "other", "mime_type": "application/pdf", "url": "/967/1/Ham_d_2002.pdf", "version": "v6.0.0" }, "type": "thesis", "title": "Statistical Electronics: Noise Processes in Integrated Communication Systems", "author": [ { "family_name": "Ham", "given_name": "Donhee", "clpid": "Ham-Donhee" } ], "thesis_advisor": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "thesis_committee": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Bruck", "given_name": "Jehoshua", "orcid": "0000-0001-8474-0812", "clpid": "Bruck-J" }, { "family_name": "Cross", "given_name": "Michael Clifford", "clpid": "Cross-M-C" }, { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Tai", "given_name": "Yu-Chong", "orcid": "0000-0001-8529-106X", "clpid": "Tai-Yu-Chong" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "This thesis presents a comprehensive investigation of noise and thermodynamics in electronic circuits and systems. This study of \"statistical electronics\" spans two disciplines, statistical thermodynamics and electronic circuit engineering, and leads to a general picture that bridges electronics and statistical thermodynamics.
\r\n\r\nOur work on statistical electronics has both scientific and engineering implications. Scientifically, this work is an extensive study of statistical thermodynamics in the context of electrical circuits, which has made several significant contributions to the understanding of noise processes in electrical circuits. The technological importance is a demonstration of how the fundamental physical considerations evolve to practical high-performance novel circuit design. The power of our fundamental approach is demonstrated through several practical circuit examples.
\r\n\r\nFirst, our investigation of fluctuations in nonlinear electrical circuits provides deep insight into the nonlinear fluctuation phenomena. Especially, the study of fluctuations in nonlinear active devices constitutes an important sector in this investigation; verifying the physical soundness of the contemporary active device noise modeling and leading to clear understanding of fluctuation-dissipation relations in nonlinear devices.
\r\n\r\nSecond, we apply statistical electronics to noise problems involved in frequency conversion, an essential function in modern RF and microwave receivers. This study leads to two novel observations of noise figure degradation due to cyclostationary noise and conversion gain enhancement, both dependent on the size of energy storing elements. This novel behavior is experimentally verified with a direct measurement of integrated switching mixers. The results provide new insight into cyclostationary noise processes in frequency conversion and optimum deisgn for switching mixers.
\r\n\r\nThird, application of statistical electronics to noise in frequency generation by self-sustained oscillators leads to a new theory of oscillator noise. This study demonstrates the direct correspondence between the phase noise and the Einstein relation; revealing the underlying physics of oscillator noise. Our approach clarifies the fluctuation-dissipation relation in oscillator noise generation, establishing a link between currently available fluctuation-based and dissipation-based phase noise. models and leading to a clear definition of loaded quality factor of ail oscillator. The novel concepts of virtual damping and linewidth compression put resonators and oscillators in a unified framework, providing immediate design optimization insight. The power of this theoretical development is demonstrated through experimental measurements of various integrated oscillators.
\r\n\r\nOur work on statistical electronics combining circuit engineering and physical science has also resulted in other useful engineering methods, such as graphical optimization, noise simulations for computer-aided design (CAD), and time-varying filter theory.
", "doi": "10.7907/tgja-7y11", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:3564", "collection": "thesis", "collection_id": "3564", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-09162005-110430", "primary_object_url": { "basename": "Pornsinsirirak_tn_2002.pdf", "content": "final", "filesize": 47885172, "license": "other", "mime_type": "application/pdf", "url": "/3564/1/Pornsinsirirak_tn_2002.pdf", "version": "v4.0.0" }, "type": "thesis", "title": "Parylene MEMS Technology for Adaptive Flow Control of Flapping Flight", "author": [ { "family_name": "Pornsinsirirak", "given_name": "Teerachai Nicholas", "clpid": "Pornsinsirirak-Teerachai-Nicholas" } ], "thesis_advisor": [ { "family_name": "Neugebauer", "given_name": "Gerry", "clpid": "Neugebauer-G" } ], "thesis_committee": [ { "family_name": "Tai", "given_name": "Yu-Chong", "orcid": "0000-0001-8529-106X", "clpid": "Tai-Yu-Chong" }, { "family_name": "Neugebauer", "given_name": "Gerry", "clpid": "Neugebauer-G" }, { "family_name": "Burdick", "given_name": "Joel Wakeman", "orcid": "0000-0002-3091-540X", "clpid": "Burdick-J-W" }, { "family_name": "Elachi", "given_name": "Charles", "clpid": "Elachi-C" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Ho", "given_name": "C-M", "clpid": "Ho-C-M" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "This thesis is the culmination of research work in developing a parylene MEMS technology to fabricate MEMS wings and large-area parylene actuator skins for real-time adaptive flow control for flapping flight applications.\r\n\r\nIn this thesis, the novel MEMS-based wing technology is presented using titanium-alloy metal (Ti-6A1-4V) as wingframe and parylene-C as wing membrane. With this technology, the ability to produce light, yet robust, 3-D wings can be achieved. The use of MEMS technology enables systematic research in terms of repeatability, size control, weight minimization, and mass production of the wings. By fabricating the wing with the photolithography and etching techniques, fast turnaround time of various wing designs can be easily obtained. The wings are optimized to utilize the flow separation to achieve a high lift coefficient, C(L), as large as five times that of the fixed-wing aircraft. The aerodynamic tests are performed in a high quality low-speed wind tunnel with velocity uniformity of 0.5% and speeds range from 1 to 10 m/s. The wind-tunnel test results are presented and discussed.\r\n\r\nAs part of the investigation to integrate MEMS actuators onto the wings for realtime adaptive flow control, the MEMS technology is developed to fabricate the first large-area wafer-sized, flexible parylene MEMS electrostatic actuator skins. The technology is first developed to fabricate parylene actuator diaphragm on a silicon chip. The actuator diaphragm is made of two metallized layers of parylene membranes with offset vent holes. Without electrostatic actuation, air can move freely from one side of the skin to the other side through the vent holes. With actuation, these vent holes are sealed and the airflow is controlled. The membrane behaves as a complete diaphragm. This function is successfully demonstrated using a 2-mm x 2-mm parylene diaphragm electrostatic actuator valves.\r\n\r\nFinally, this technology is applied to fabricate large area wafer-sized actuator skins. The skins contain only parylene and metalized electrodes and have no bulk silicon as a structural component. Plate and check-valved skin types are fabricated and both are integrated onto the MEMS wings for aerodynamic flow control. The integration of micro-valved actuators has shown significant effect on the aerodynamic performance of the flapping flight. The wind-tunnel test results are analyzed and discussed in detail in this thesis.\r\n", "doi": "10.7907/jtjd-dd33", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:2129", "collection": "thesis", "collection_id": "2129", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05272004-094928", "primary_object_url": { "basename": "Aoki_i_2002.pdf", "content": "final", "filesize": 26641555, "license": "other", "mime_type": "application/pdf", "url": "/2129/1/Aoki_i_2002.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Distributed Active Transformer for Integrated Power Amplification", "author": [ { "family_name": "Aoki", "given_name": "Ichiro", "clpid": "Aoki-Ichiro" } ], "thesis_advisor": [ { "family_name": "Janda", "given_name": "Kenneth C.", "clpid": "Janda-K-C" } ], "thesis_committee": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Bruck", "given_name": "Jehoshua", "orcid": "0000-0001-8474-0812", "clpid": "Bruck-J" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Tai", "given_name": "Yu-Chong", "orcid": "0000-0001-8529-106X", "clpid": "Tai-Yu-Chong" }, { "family_name": "Janda", "given_name": "Kenneth C.", "clpid": "Janda-K-C" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "A novel on-chip impedance transformation and power-combining technique, the distributed active transformer (DAT) is introduced. It overcomes the fundamental difficulties presented by silicon technology in the design of integrated rf power amplifiers. This technique efficiently combines several low-voltage push-pull amplifiers and simultaneously performs an impedance transformation to produce a larger output power while maintaining a 50\u03a9 match. It also uses virtual ac grounds and magnetic couplings extensively to eliminate the need for any off-chip component, such as tuned bonding wires or external inductors. Furthermore, it desensitizes the operation of the amplifier to the inductance of bonding wires making the design more repeatable.
\r\n\r\nIn this work, the performance of the introduced DAT structure is compared to that of conventional on-chip impedance transformation methods. Their fundamental power-efficiency limitations in the design of high-power fully-integrated amplifiers in standard silicon process technologies are analyzed and the DAT is demonstrated to be more efficient. Furthermore, different classes of power amplification operations and their use in DAT power amplifiers are studied.
\r\n\r\nTo demonstrate the feasibility of this concept several silicon integrated power amplifiers have been fabricated and measured including a 2.4-GHz, 2-W, 2-V truly fully-integrated power amplifier with 50\u03a9 on-chip input and output matching using 0.35\u00b5m CMOS transistors. It achieves a power added efficiency (PAE) of 41 % at this power level, demonstrating for the first time a truly fully-integrated watt-level GHz range CMOS power amplifier. It can also produce 450mW using a 1 V supply. A two stage DAT prototype, also at 2.4GHz using the same technology, operates with higher gain and lower supply voltage achieving 1-W output power, 30% PAE, and 14-dB gain with 1.15-V supply.
", "doi": "10.7907/6XMD-MR86", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:1512", "collection": "thesis", "collection_id": "1512", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-04262005-152703", "primary_object_url": { "basename": "Kee_s_2002.pdf", "content": "final", "filesize": 36463553, "license": "other", "mime_type": "application/pdf", "url": "/1512/1/Kee_s_2002.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "The Class E/F Family of Harmonic-Tuned Switching Power Amplifiers", "author": [ { "family_name": "Kee", "given_name": "Scott David", "clpid": "Kee-Scott-David" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "McEliece", "given_name": "Robert J.", "clpid": "McEliece-R-J" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nA new family of harmonic-tuned switching amplifiers is introduced having the beneficial features of the class-E tuning while allowing improved performance to be achieved through additional harmonic tuning. This E/F family may be tuned to achieve the ZVS/ZdVS switching features characteristic of the class-E amplifier and, like the class-E tuning, accounts and compensates for the effect of the switch parallel capacitance. By tuning one or more overtones to the [...] tuning, however, the switching waveforms may be improved, lowering the peak voltage and reducing the RMS current. Additionally, the tolerance to large switch parallel capacitance is generally improved so that a larger switching device may be used, allowing reduction of the on-resistance. Due to these factors, the efficiency of E/F amplifiers is expected to exceed that of class E.\r\n\r\nTo demonstrate these advantages, methods of estimating the optimal efficiency of switching amplifiers using waveform properties are given. A general solution technique is then presented which allows the calculation of the ZVS tuning requirements and the resulting switching waveforms for an arbitrary harmonic tuning. Using these two tools, switching waveforms and resulting efficiency estimates are calculated for E/F amplifier tunings, which are then compared to class E.\r\n\r\nFinally, potential application areas of the E/F technique are explored, and measured results of several first-generation E/F amplifiers are presented. Aside from efficiency benefits, E/F amplifiers also may achieve load-invariance, dual- and multi-band operation, high volumetric power densities, and efficient integrated circuit implementation using the Aoki distributed active transformer power combining structure.\r\n", "doi": "10.7907/MD86-FX51", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:2129", "collection": "thesis", "collection_id": "2129", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-05272004-094928", "primary_object_url": { "basename": "Aoki_i_2002.pdf", "content": "final", "filesize": 26641555, "license": "other", "mime_type": "application/pdf", "url": "/2129/1/Aoki_i_2002.pdf", "version": "v3.0.0" }, "type": "thesis", "title": "Distributed Active Transformer for Integrated Power Amplification", "author": [ { "family_name": "Aoki", "given_name": "Ichiro", "clpid": "Aoki-Ichiro" } ], "thesis_advisor": [ { "family_name": "Janda", "given_name": "Kenneth C.", "clpid": "Janda-K-C" } ], "thesis_committee": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Bruck", "given_name": "Jehoshua", "orcid": "0000-0001-8474-0812", "clpid": "Bruck-J" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Tai", "given_name": "Yu-Chong", "orcid": "0000-0001-8529-106X", "clpid": "Tai-Yu-Chong" }, { "family_name": "Janda", "given_name": "Kenneth C.", "clpid": "Janda-K-C" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "A novel on-chip impedance transformation and power-combining technique, the distributed active transformer (DAT) is introduced. It overcomes the fundamental difficulties presented by silicon technology in the design of integrated rf power amplifiers. This technique efficiently combines several low-voltage push-pull amplifiers and simultaneously performs an impedance transformation to produce a larger output power while maintaining a 50\u03a9 match. It also uses virtual ac grounds and magnetic couplings extensively to eliminate the need for any off-chip component, such as tuned bonding wires or external inductors. Furthermore, it desensitizes the operation of the amplifier to the inductance of bonding wires making the design more repeatable.
\r\n\r\nIn this work, the performance of the introduced DAT structure is compared to that of conventional on-chip impedance transformation methods. Their fundamental power-efficiency limitations in the design of high-power fully-integrated amplifiers in standard silicon process technologies are analyzed and the DAT is demonstrated to be more efficient. Furthermore, different classes of power amplification operations and their use in DAT power amplifiers are studied.
\r\n\r\nTo demonstrate the feasibility of this concept several silicon integrated power amplifiers have been fabricated and measured including a 2.4-GHz, 2-W, 2-V truly fully-integrated power amplifier with 50\u03a9 on-chip input and output matching using 0.35\u00b5m CMOS transistors. It achieves a power added efficiency (PAE) of 41 % at this power level, demonstrating for the first time a truly fully-integrated watt-level GHz range CMOS power amplifier. It can also produce 450mW using a 1 V supply. A two stage DAT prototype, also at 2.4GHz using the same technology, operates with higher gain and lower supply voltage achieving 1-W output power, 30% PAE, and 14-dB gain with 1.15-V supply.
", "doi": "10.7907/6XMD-MR86", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:1512", "collection": "thesis", "collection_id": "1512", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-04262005-152703", "primary_object_url": { "basename": "Kee_s_2002.pdf", "content": "final", "filesize": 36463553, "license": "other", "mime_type": "application/pdf", "url": "/1512/1/Kee_s_2002.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "The Class E/F Family of Harmonic-Tuned Switching Power Amplifiers", "author": [ { "family_name": "Kee", "given_name": "Scott David", "clpid": "Kee-Scott-David" } ], "thesis_advisor": [ { "family_name": "Readhead", "given_name": "Anthony C. S.", "clpid": "Readhead-A-C-S" } ], "thesis_committee": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "McEliece", "given_name": "Robert J.", "clpid": "McEliece-R-J" }, { "family_name": "Weinreb", "given_name": "Sander", "orcid": "0000-0002-9353-6204", "clpid": "Weinreb-S" }, { "family_name": "Readhead", "given_name": "Anthony C. S.", "orcid": "0000-0001-9152-961X", "clpid": "Readhead-A-C-S" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document.\r\n\r\nA new family of harmonic-tuned switching amplifiers is introduced having the beneficial features of the class-E tuning while allowing improved performance to be achieved through additional harmonic tuning. This E/F family may be tuned to achieve the ZVS/ZdVS switching features characteristic of the class-E amplifier and, like the class-E tuning, accounts and compensates for the effect of the switch parallel capacitance. By tuning one or more overtones to the [...] tuning, however, the switching waveforms may be improved, lowering the peak voltage and reducing the RMS current. Additionally, the tolerance to large switch parallel capacitance is generally improved so that a larger switching device may be used, allowing reduction of the on-resistance. Due to these factors, the efficiency of E/F amplifiers is expected to exceed that of class E.\r\n\r\nTo demonstrate these advantages, methods of estimating the optimal efficiency of switching amplifiers using waveform properties are given. A general solution technique is then presented which allows the calculation of the ZVS tuning requirements and the resulting switching waveforms for an arbitrary harmonic tuning. Using these two tools, switching waveforms and resulting efficiency estimates are calculated for E/F amplifier tunings, which are then compared to class E.\r\n\r\nFinally, potential application areas of the E/F technique are explored, and measured results of several first-generation E/F amplifiers are presented. Aside from efficiency benefits, E/F amplifiers also may achieve load-invariance, dual- and multi-band operation, high volumetric power densities, and efficient integrated circuit implementation using the Aoki distributed active transformer power combining structure.\r\n", "doi": "10.7907/MD86-FX51", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:6263", "collection": "thesis", "collection_id": "6263", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03022011-131111881", "primary_object_url": { "basename": "Penzes_pi_2002.pdf", "content": "final", "filesize": 105482562, "license": "other", "mime_type": "application/pdf", "url": "/6263/1/Penzes_pi_2002.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Energy-Delay Complexity of Asynchronous Circuits", "author": [ { "family_name": "P\u00e9nzes", "given_name": "Paul Ivan", "clpid": "P\u00e9nzes-Paul-Ivan" } ], "thesis_advisor": [ { "family_name": "Martin", "given_name": "Alain J.", "clpid": "Martin-A-J" } ], "thesis_committee": [ { "family_name": "Martin", "given_name": "Alain J.", "clpid": "Martin-A-J" }, { "family_name": "DeHon", "given_name": "Andre", "clpid": "DeHon-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Hickey", "given_name": "Jason J.", "clpid": "Hickey-J-J" }, { "family_name": "Nystr\u00f6em", "given_name": "Mika", "clpid": "Nystr\u00f6em-M" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "In this thesis, a circuit-level theory of energy-delay complexity is developed for asynchronous circuits. The energy-delay efficiency of a circuit is characterized using the metric Et^n , where E is the energy consumed by the computation, t is the delay of the computation, and n is a positive number that reflects a chosen trade-off between\r\nenergy and delay. Based on theoretical and experimental evidence, it is argued that for a circuit optimized for minimal Et^n, the consumed energy is independent, in first\r\napproximation, of the types of gates (NAND, NOR, etc.) used by the circuit and is solely dependent on n and the total amount of wiring capacitance switched during computation. Conversely, the circuit speed is independent, in first approximation, of the wiring capacitance and depends only on n and the types of gates used.\r\n\r\nThe complexity model allows us to compare the energy-delay efficiency of two circuits implementing the same computation. On the other hand, the complexity model itself does not say much about the actual transistor sizes that achieve the optimum. For this reason, the problem of transistor sizing of circuits optimized for Et^n is investigated, as well. A set of analytical formulas that closely approximate the optimal transistor sizes are explored. An efficient iteration procedure that can further\r\nimprove the original analytical solution is then studied. Based on these results, a novel transistor-sizing algorithm for energy-delay efficiency is introduced.\r\n\r\nIt is shown that the Et^n metric for the energy-delay efficiency index n \u2265 0 characterizes any optimal trade-off between the energy and the delay of a computation. For\r\nexample, any problem of minimizing the energy of a system for a given target delay can be restated as minimizing Et^n for a certain n. The notion of minimum-energy function is developed and applied to the parallel and sequential composition of circuits in general and, in particular, to circuits optimized through transistor sizing and\r\nvoltage scaling. Bounds on the energy and delay of the optimized circuits are computed, and necessary and sufficient conditions are given under which these bounds are\r\nreached. Necessary and sufficient conditions are also given under which components of a design can be optimized independently so as to yield a global optimum when\r\ncomposed. Through these applications, the utility of the minimum-energy function is demonstrated. The use of this minimum-energy function yields practical insight into\r\nways of improving the overall energy-delay efficiency of circuits.\r\n", "doi": "10.7907/9jpj-5s67", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:6263", "collection": "thesis", "collection_id": "6263", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:03022011-131111881", "primary_object_url": { "basename": "Penzes_pi_2002.pdf", "content": "final", "filesize": 105482562, "license": "other", "mime_type": "application/pdf", "url": "/6263/1/Penzes_pi_2002.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Energy-Delay Complexity of Asynchronous Circuits", "author": [ { "family_name": "P\u00e9nzes", "given_name": "Paul Ivan", "clpid": "P\u00e9nzes-Paul-Ivan" } ], "thesis_advisor": [ { "family_name": "Martin", "given_name": "Alain J.", "clpid": "Martin-A-J" } ], "thesis_committee": [ { "family_name": "Martin", "given_name": "Alain J.", "clpid": "Martin-A-J" }, { "family_name": "DeHon", "given_name": "Andre", "clpid": "DeHon-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Hickey", "given_name": "Jason J.", "clpid": "Hickey-J-J" }, { "family_name": "Nystr\u00f6em", "given_name": "Mika", "clpid": "Nystr\u00f6em-M" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "In this thesis, a circuit-level theory of energy-delay complexity is developed for asynchronous circuits. The energy-delay efficiency of a circuit is characterized using the metric Et^n , where E is the energy consumed by the computation, t is the delay of the computation, and n is a positive number that reflects a chosen trade-off between\r\nenergy and delay. Based on theoretical and experimental evidence, it is argued that for a circuit optimized for minimal Et^n, the consumed energy is independent, in first\r\napproximation, of the types of gates (NAND, NOR, etc.) used by the circuit and is solely dependent on n and the total amount of wiring capacitance switched during computation. Conversely, the circuit speed is independent, in first approximation, of the wiring capacitance and depends only on n and the types of gates used.\r\n\r\nThe complexity model allows us to compare the energy-delay efficiency of two circuits implementing the same computation. On the other hand, the complexity model itself does not say much about the actual transistor sizes that achieve the optimum. For this reason, the problem of transistor sizing of circuits optimized for Et^n is investigated, as well. A set of analytical formulas that closely approximate the optimal transistor sizes are explored. An efficient iteration procedure that can further\r\nimprove the original analytical solution is then studied. Based on these results, a novel transistor-sizing algorithm for energy-delay efficiency is introduced.\r\n\r\nIt is shown that the Et^n metric for the energy-delay efficiency index n \u2265 0 characterizes any optimal trade-off between the energy and the delay of a computation. For\r\nexample, any problem of minimizing the energy of a system for a given target delay can be restated as minimizing Et^n for a certain n. The notion of minimum-energy function is developed and applied to the parallel and sequential composition of circuits in general and, in particular, to circuits optimized through transistor sizing and\r\nvoltage scaling. Bounds on the energy and delay of the optimized circuits are computed, and necessary and sufficient conditions are given under which these bounds are\r\nreached. Necessary and sufficient conditions are also given under which components of a design can be optimized independently so as to yield a global optimum when\r\ncomposed. Through these applications, the utility of the minimum-energy function is demonstrated. The use of this minimum-energy function yields practical insight into\r\nways of improving the overall energy-delay efficiency of circuits.\r\n", "doi": "10.7907/9jpj-5s67", "publication_date": "2002", "thesis_type": "phd", "thesis_year": "2002" }, { "id": "thesis:6147", "collection": "thesis", "collection_id": "6147", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10152010-145548970", "primary_object_url": { "basename": "Nystrom_m_2001.pdf", "content": "final", "filesize": 7148606, "license": "other", "mime_type": "application/pdf", "url": "/6147/1/Nystrom_m_2001.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Asynchronous Pulse Logic", "author": [ { "family_name": "Nystr\u00f6m", "given_name": "Mika", "clpid": "Nystr\u00f6m-Mika" } ], "thesis_advisor": [ { "family_name": "Martin", "given_name": "Alain J.", "clpid": "Martin-A-J" } ], "thesis_committee": [ { "family_name": "Martin", "given_name": "Alain J.", "clpid": "Martin-A-J" }, { "family_name": "DeHon", "given_name": "Andre", "clpid": "DeHon-A" }, { "family_name": "Manohar", "given_name": "Rajit", "clpid": "Manohar-R" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "This thesis explores a new way of computing with CMOS digital circuits, single-track\u2014handshake asynchronous pulse-logic (STAPL). These circuits are similar to quasi delay-insensitive (QDI) circuits, but the normal four-phase QDI handshake is replaced with a simpler two-phase pulsed handshake. While a delay-insensitive two-phase handshake requires complicated decoding circuits, the pulsed handshake maintains the simpler, electrically beneficial signaling senses of four-phase handshaking by using timing assumptions that are easy to meet.
\r\n\r\nWe cover many aspects of designing moderately large digital systems out of STAPL circuits, from the communicating-process level to the production-rule and transistor level.
\r\n\r\nWe study the theory of operation of pulsed asynchronous circuits, starting with simple pulse repeaters; hence we progress to a general theory of operation for pulsed asynchronous circuits. This theory is a generalization of the theory of operation of synchronous digital circuits.
\r\n\r\nWe then develop the family of STAPL circuits. This is a complete family of dataflow processes: the presented circuits can compute unconditionally as well as conditionally; they can also store state and arbitrate.
\r\n\r\nNext, we present some aspects of automatic design-tools for compiling from a higher-level description to STAPL circuits. Many of these aspects apply equally well to tools for QDI circuits; in particular, we study boolean-simplification operations that may be used for improving the performance of slack-elastic asynchronous systems.
\r\n\r\nFinally, a simple 32-bit microprocessor is presented as a demonstration that the circuits and design methods work as described. Comparisons are made, mainly with QDI asynchronous design-styles: SPICE simulations in 0.6-\u00b5m CMOS suggest that a system built out of automatically compiled STAPL circuits performs at about three times higher throughput (650-700 MHz in 0.6-\u00b5m CMOS) compared with a similar system built out of carefully hand-compiled QDI circuits; the STAPL system uses about twice the energy per operation and twice the area; in other words, the STAPL system improves on the QDI system by four to five times as measured by the Et^2 and At^2 metrics.
", "doi": "10.7907/B107-MW15", "publication_date": "2001", "thesis_type": "phd", "thesis_year": "2001" }, { "id": "thesis:6084", "collection": "thesis", "collection_id": "6084", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10012010-095709235", "primary_object_url": { "basename": "Desai_as_2000.pdf", "content": "final", "filesize": 6375905, "license": "other", "mime_type": "application/pdf", "url": "/6084/1/Desai_as_2000.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Micromachined Devices for an Airborne Bio-Particle Analysis System", "author": [ { "family_name": "Desai", "given_name": "Amish S.", "clpid": "Desai-Amish-S" } ], "thesis_advisor": [ { "family_name": "Tai", "given_name": "Yu-Chong", "orcid": "0000-0001-8529-106X", "clpid": "Tai-Yu-Chong" } ], "thesis_committee": [ { "family_name": "Tai", "given_name": "Yu-Chong", "orcid": "0000-0001-8529-106X", "clpid": "Tai-Yu-Chong" }, { "family_name": "Goodwin", "given_name": "David G.", "clpid": "Goodwin-D-G" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Rosenberg", "given_name": "Jim", "orcid": "0009-0006-8388-7437", "clpid": "Rosenberg-J" }, { "family_name": "Sovero", "given_name": "Emilio Andres", "clpid": "Sovero-Emilio-Andres" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The goal of this thesis is to develop micromachined devices for an automated miniaturized airborne bio-particle analysis system. The realization of such a system is complex requiring a particle capture, transport, collection, sample preparation, and analysis. Accordingly, microelectromechanical systems (MEMS) teams have studied and developed micro-pumps, valves, channels as building blocks for a miniature chemical analysis system. In this thesis, novel micromachined solutions to some of these tasks are presented. Specifically, the development of: 1) a low voltage, air-based electrostatic particle transportation system, 2) an air-to-liquid interface design for transport of airborne particles into a liquid environment 3) a micro-chip electrospray (ES) mass spectrometer interface for small volume(nL) mass spectrometry, 4) and fast mixers (<100\u03bcs) for the study of chemical reaction kinetics. The particle transport system consists of 3-phase electrode arrays covered by photoresist and Teflon. Extensive testing of this system has been done using a variety of insulation materials, thicknesses (0-12\u03bcm), particle sizes (1-10\u03bcm), particle materials (metal, glass, polystyrene, spores, etc.), waveforms, frequencies, and voltages. Although previous literature claimed it impractical to electrostatically transport particles with sizes of 5-10\u03bcm due to complex surface forces, this effort actually demonstrates 90% transportation efficiencies with the optimal combination of insulation thickness, electrode geometry, and insulation material. As the second step, this particle transportation technology has also been integrated with an active micromachined filter and an air-to-liquid silicone rubber interface. Two methods of air to liquid particle transport were explored \u2014 moving particles across a stationary fluid meniscus and the other, moving meniscus across stationary particles. Third, the development of a micron-sized MEMS nozzle (1-3 \u03bcm orifice diameters) is presented with successful demonstration of its application for electrospray ionization mass spectroscopy. MEMS scaling issues were verified with the flow visualization of the Taylor Cone on this nozzle. Fourth, a 1 cm x 1 cm x 1 mm DRIE silicon mixer capable of initiating and quenching (starting and stopping) chemical reactions in intervals as short as 100 \u03bcs was characterized by employing two carefully chosen chemical reactions with reaction time constants of 3 ms and 9 ms along with visualization techniques using dyes and acid-base indicators.", "doi": "10.7907/ge1w-t045", "publication_date": "2000", "thesis_type": "phd", "thesis_year": "2000" }, { "id": "thesis:6108", "collection": "thesis", "collection_id": "6108", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10062010-101242368", "primary_object_url": { "basename": "Li_l_2000.pdf", "content": "final", "filesize": 7429688, "license": "other", "mime_type": "application/pdf", "url": "/6108/1/Li_l_2000.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Adaptive Receiver Design and Optimal Resource Allocation Strategies for Fading Channels", "author": [ { "family_name": "Li", "given_name": "Lifang", "clpid": "Li-Lifang" } ], "thesis_advisor": [ { "family_name": "Goodman", "given_name": "Rodney M.", "clpid": "Goodman-R-M" } ], "thesis_committee": [ { "family_name": "Goldsmith", "given_name": "Andrea Jo", "orcid": "0000-0001-5686-800X", "clpid": "Goldsmith-A-J" }, { "family_name": "Divsalar", "given_name": "Dariush", "orcid": "0000-0001-9176-3078", "clpid": "Divsalar-D" }, { "family_name": "McEliece", "given_name": "Robert J.", "clpid": "McEliece-R-J" }, { "family_name": "Effros", "given_name": "Michelle", "orcid": "0000-0003-3757-0675", "clpid": "Effros-M" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The mobile wireless environment has been a challenge to reliable communications because of the time-varying nature of the channel. Detrimental effects such as path loss, shadowing, and multipath fading can greatly attenuate the transmitted signal. Therefore, adaptive channel estimation and data detecting algorithms must be designed for such channels. Moreover, in a multi-user system, dynamic resource allocation is an important means to transmit information efficiently through the varying channel.
\r\n\r\nIn this thesis we first propose two adaptive feedback maximum-likelihood detection techniques, a decision-feedback decoder and an output-feedback decoder, for coded signals transmitted over channels with correlated fading. Both analysis and simulation results demonstrate that they have far better performance than the conventional decoder. We also propose a simple improvement to conventional decoders by using a weighted metric. The BER performance of all these decoders is analyzed through a sliding window decoding method.
\r\n\r\nNext we derive the ergodic (Shannon) capacity region and optimal dynamic resource allocation for an M-user fading broadcast channel under code-division with and without successive decoding, time-division, and frequency-division. For this channel we also derive the outage and zero-outage capacity regions and the corresponding optimal resource allocation strategies under different spectrum-sharing techniques. We obtain the outage capacity region implicitly by deriving the minimum common outage probability or the outage probability region for a given rate vector. The corresponding optimal power allocation scheme is a multi-user generalization of the single-user threshold-decision rule.
\r\n\r\nFinally, we obtain the outage capacity region and optimal power allocation for fading multiple access channels. Successive decoding is proved to be optimal and iterative algorithms are proposed to obtain the optimal decoding order and power allocation in each fading state under the average power and outage probability constraints of each user. We also obtain the average power regions that can support a rate vector with the given average outage probability of each user satisfied.
\r\n", "doi": "10.7907/ata8-3r29", "publication_date": "2000", "thesis_type": "phd", "thesis_year": "2000" }, { "id": "thesis:480", "collection": "thesis", "collection_id": "480", "cite_using_url": "https://resolver.caltech.edu/CaltechETD:etd-02032004-163517", "primary_object_url": { "basename": "thesis.pdf", "content": "final", "filesize": 2085207, "license": "other", "mime_type": "application/pdf", "url": "/480/1/thesis.pdf", "version": "v2.0.0" }, "type": "thesis", "title": "Dual polarized and balanced receivers at millimeter and submillimeter wavelengths", "author": [ { "family_name": "Chattopadhyay", "given_name": "Goutam", "orcid": "0000-0001-7942-5025", "clpid": "Chattopadhyay-Goutam" } ], "thesis_advisor": [ { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" } ], "thesis_committee": [ { "family_name": "Rutledge", "given_name": "David B.", "clpid": "Rutledge-D-B" }, { "family_name": "Zmuidzinas", "given_name": "Jonas", "clpid": "Zmuidzinas-J" }, { "family_name": "Hajimiri", "given_name": "Ali", "clpid": "Hajimiri-A" }, { "family_name": "Carlstrom", "given_name": "John E.", "clpid": "Carlstrom-J-E" }, { "family_name": "Weinreb", "given_name": "Sander", "clpid": "Weinreb-S" } ], "local_group": [ { "literal": "Caltech Submillimeter Observatory" }, { "literal": "Astronomy Department" }, { "literal": "div_eng" } ], "abstract": "Dramatic advances in millimeter and submillimeter wave receivers in recent years have resulted from the development of superconductor insulator superconductor (SIS) mixers, which now offer unsurpassed performance from 70 GHz to 1 THz. To increase the sensitivity of the receivers further at these frequencies, one needs to use dual-polarized and balanced receivers. When both the polarizations are received simultaneously, there is a square root of two improvement in the signal to noise ratio (SNR). Balanced mixers improve the sensitivity of receivers by suppressing local oscillator (LO) amplitude modulation (AM) noise and rejecting LO thermal noise. This thesis describes the design, fabrication and performance of mixers and components for low noise dual-polarized and balanced receivers at millimeter and submillimeter wavelengths both in quasi-optical and waveguide configurations. The quasi-optical receiver utilizes a novel cross-slot antenna on a silicon hyperhemispherical lens, two junction tuning circuits, niobium trilayer junctions, and an IF circuit containing a lumped element 180 degree hybrid. The antenna has four feed points, two for each polarization; and each feed point is coupled to a two-junction SIS mixer. For dual polarization operation, the mixer is mounted in such a way that a single LO can pump the junctions for both the polarizations. For the balanced receiver, the LO and the RF signals are coupled to the mixer in orthogonal polarizations using a wire-grid polarizer. For waveguide dual polarization receivers, a moderately broadband septum ortho-mode transducer (OMT) is designed and experimental results are presented at millimeter wavelengths. Broadband finline OMTs are investigated for possible use at millimeter wavelengths, and experimental results of a finline OMT is presented at X-band.", "doi": "10.7907/RMVX-0619", "publication_date": "2000", "thesis_type": "phd", "thesis_year": "2000" }, { "id": "thesis:6084", "collection": "thesis", "collection_id": "6084", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10012010-095709235", "primary_object_url": { "basename": "Desai_as_2000.pdf", "content": "final", "filesize": 6375905, "license": "other", "mime_type": "application/pdf", "url": "/6084/1/Desai_as_2000.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Micromachined Devices for an Airborne Bio-Particle Analysis System", "author": [ { "family_name": "Desai", "given_name": "Amish S.", "clpid": "Desai-Amish-S" } ], "thesis_advisor": [ { "family_name": "Tai", "given_name": "Yu-Chong", "orcid": "0000-0001-8529-106X", "clpid": "Tai-Yu-Chong" } ], "thesis_committee": [ { "family_name": "Tai", "given_name": "Yu-Chong", "orcid": "0000-0001-8529-106X", "clpid": "Tai-Yu-Chong" }, { "family_name": "Goodwin", "given_name": "David G.", "clpid": "Goodwin-D-G" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Rosenberg", "given_name": "Jim", "orcid": "0009-0006-8388-7437", "clpid": "Rosenberg-J" }, { "family_name": "Sovero", "given_name": "Emilio Andres", "clpid": "Sovero-Emilio-Andres" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The goal of this thesis is to develop micromachined devices for an automated miniaturized airborne bio-particle analysis system. The realization of such a system is complex requiring a particle capture, transport, collection, sample preparation, and analysis. Accordingly, microelectromechanical systems (MEMS) teams have studied and developed micro-pumps, valves, channels as building blocks for a miniature chemical analysis system. In this thesis, novel micromachined solutions to some of these tasks are presented. Specifically, the development of: 1) a low voltage, air-based electrostatic particle transportation system, 2) an air-to-liquid interface design for transport of airborne particles into a liquid environment 3) a micro-chip electrospray (ES) mass spectrometer interface for small volume(nL) mass spectrometry, 4) and fast mixers (<100\u03bcs) for the study of chemical reaction kinetics. The particle transport system consists of 3-phase electrode arrays covered by photoresist and Teflon. Extensive testing of this system has been done using a variety of insulation materials, thicknesses (0-12\u03bcm), particle sizes (1-10\u03bcm), particle materials (metal, glass, polystyrene, spores, etc.), waveforms, frequencies, and voltages. Although previous literature claimed it impractical to electrostatically transport particles with sizes of 5-10\u03bcm due to complex surface forces, this effort actually demonstrates 90% transportation efficiencies with the optimal combination of insulation thickness, electrode geometry, and insulation material. As the second step, this particle transportation technology has also been integrated with an active micromachined filter and an air-to-liquid silicone rubber interface. Two methods of air to liquid particle transport were explored \u2014 moving particles across a stationary fluid meniscus and the other, moving meniscus across stationary particles. Third, the development of a micron-sized MEMS nozzle (1-3 \u03bcm orifice diameters) is presented with successful demonstration of its application for electrospray ionization mass spectroscopy. MEMS scaling issues were verified with the flow visualization of the Taylor Cone on this nozzle. Fourth, a 1 cm x 1 cm x 1 mm DRIE silicon mixer capable of initiating and quenching (starting and stopping) chemical reactions in intervals as short as 100 \u03bcs was characterized by employing two carefully chosen chemical reactions with reaction time constants of 3 ms and 9 ms along with visualization techniques using dyes and acid-base indicators.", "doi": "10.7907/ge1w-t045", "publication_date": "2000", "thesis_type": "phd", "thesis_year": "2000" }, { "id": "thesis:6108", "collection": "thesis", "collection_id": "6108", "cite_using_url": "https://resolver.caltech.edu/CaltechTHESIS:10062010-101242368", "primary_object_url": { "basename": "Li_l_2000.pdf", "content": "final", "filesize": 7429688, "license": "other", "mime_type": "application/pdf", "url": "/6108/1/Li_l_2000.pdf", "version": "v5.0.0" }, "type": "thesis", "title": "Adaptive Receiver Design and Optimal Resource Allocation Strategies for Fading Channels", "author": [ { "family_name": "Li", "given_name": "Lifang", "clpid": "Li-Lifang" } ], "thesis_advisor": [ { "family_name": "Goodman", "given_name": "Rodney M.", "clpid": "Goodman-R-M" } ], "thesis_committee": [ { "family_name": "Goldsmith", "given_name": "Andrea Jo", "orcid": "0000-0001-5686-800X", "clpid": "Goldsmith-A-J" }, { "family_name": "Divsalar", "given_name": "Dariush", "orcid": "0000-0001-9176-3078", "clpid": "Divsalar-D" }, { "family_name": "McEliece", "given_name": "Robert J.", "clpid": "McEliece-R-J" }, { "family_name": "Effros", "given_name": "Michelle", "orcid": "0000-0003-3757-0675", "clpid": "Effros-M" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "local_group": [ { "literal": "div_eng" } ], "abstract": "The mobile wireless environment has been a challenge to reliable communications because of the time-varying nature of the channel. Detrimental effects such as path loss, shadowing, and multipath fading can greatly attenuate the transmitted signal. Therefore, adaptive channel estimation and data detecting algorithms must be designed for such channels. Moreover, in a multi-user system, dynamic resource allocation is an important means to transmit information efficiently through the varying channel.
\r\n\r\nIn this thesis we first propose two adaptive feedback maximum-likelihood detection techniques, a decision-feedback decoder and an output-feedback decoder, for coded signals transmitted over channels with correlated fading. Both analysis and simulation results demonstrate that they have far better performance than the conventional decoder. We also propose a simple improvement to conventional decoders by using a weighted metric. The BER performance of all these decoders is analyzed through a sliding window decoding method.
\r\n\r\nNext we derive the ergodic (Shannon) capacity region and optimal dynamic resource allocation for an M-user fading broadcast channel under code-division with and without successive decoding, time-division, and frequency-division. For this channel we also derive the outage and zero-outage capacity regions and the corresponding optimal resource allocation strategies under different spectrum-sharing techniques. We obtain the outage capacity region implicitly by deriving the minimum common outage probability or the outage probability region for a given rate vector. The corresponding optimal power allocation scheme is a multi-user generalization of the single-user threshold-decision rule.
\r\n\r\nFinally, we obtain the outage capacity region and optimal power allocation for fading multiple access channels. Successive decoding is proved to be optimal and iterative algorithms are proposed to obtain the optimal decoding order and power allocation in each fading state under the average power and outage probability constraints of each user. We also obtain the average power regions that can support a rate vector with the given average outage probability of each user satisfied.
\r\n", "doi": "10.7907/ata8-3r29", "publication_date": "2000", "thesis_type": "phd", "thesis_year": "2000" } ]