Flexible phased arrays can address new applications and provide new capabilities in communications, radar, sensing, and wireless power transfer due to their novel form factor, which enables rapid deployment, conformity, and mass and size advantages. However, the variable position of their elements makes them vulnerable to the deleterious effects of incoherence. This problem can be addressed by reconstructing the shape of the array and compensating for the change in the position of the radiator at the system level. This article presents a method for reconstructing the shape of a 2-D flexible phased array using only measurements of mutual coupling between the array elements. The method consists of an optimization loop: predicting the coupling for a given shape, comparing the prediction to measurement, and iterating through shape perturbations using the Levenberg–Marquardt algorithm. Shape reconstruction is demonstrated with a ≈0.08 λ mean position error across a wide variety of shape configurations on a passive 8×8 flexible patch antenna array operating at ≈5 GHz.
", "doi": "10.1109/tmtt.2025.3649052", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2026-04", "series_number": "4", "volume": "74", "issue": "4", "pages": "3870-3888" }, { "id": "authors:fa161-eey24", "collection": "authors", "collection_id": "fa161-eey24", "cite_using_url": "https://authors.library.caltech.edu/records/fa161-eey24", "type": "article", "title": "Space solar power generation: A viable system proposal and technoeconomic analysis", "author": [ { "family_name": "Mizrahi", "given_name": "Oren S.", "orcid": "0000-0003-4271-8822" }, { "family_name": "Jahelka", "given_name": "Phillip", "orcid": "0000-0002-1460-7933" }, { "family_name": "Gdoutos", "given_name": "Eleftherios", "orcid": "0000-0003-3529-4726", "clpid": "Gdoutos-Eleftherios-E" }, { "family_name": "Brunet", "given_name": "Jesse", "orcid": "0009-0002-8614-3362" }, { "family_name": "Ayling", "given_name": "Alex", "orcid": "0009-0008-5440-7785" }, { "family_name": "Fikes", "given_name": "Austin", "orcid": "0000-0003-4889-5782" }, { "family_name": "Wu", "given_name": "Ailec" }, { "family_name": "Madonna", "given_name": "Richard", "orcid": "0000-0002-8191-4896" }, { "family_name": "Atwater", "given_name": "Harry A.", "orcid": "0000-0001-9435-0201", "clpid": "Atwater-H-A" }, { "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" } ], "abstract": "This paper presents a distributed space solar power system that converts solar insolation into microwave power and beams it to Earth. This system, composed of a power station of close-flying modules residing in geostationary orbit, can form dynamically programmable focal points on Earth to provide dispatchable power on demand. Modules are composed of flexible phased array sheets hosting a self-synchronizing network of integrated circuits and antennas that convert DC power from photovoltaic cells into radiated RF energy. The sheets are coiled into a compact payload, launched, and deployed in orbit. Here, we present a detailed technoeconomic analysis of the proposed system, with investigations into mass, cost to produce and launch, and a levelized cost of energy (LCOE). Our analyses demonstrate that with 10 years of technology development, maturation, and scaling, the proposed 10 GHz system can deliver electricity at 9.4 \u00a2/kWh\u2014competitive with the cheapest clean energy sources available today.", "doi": "10.1016/j.joule.2025.101928", "issn": "2542-4785", "publisher": "Cell Press", "publication": "Joule", "publication_date": "2025-06-18", "series_number": "6", "volume": "9", "issue": "6", "pages": "101928" }, { "id": "authors:46qzv-gkr66", "collection": "authors", "collection_id": "46qzv-gkr66", "cite_using_url": "https://authors.library.caltech.edu/records/46qzv-gkr66", "type": "article", "title": "Phase Noise and Dynamic Range in Radar Arrays", "author": [ { "family_name": "Nooshabadi", "given_name": "Samir", "orcid": "0000-0003-1645-0009", "clpid": "Nooshabadi-Samir" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "In this work, the phase noise-induced sidelobes that limit radar dynamic range are analyzed. An analytical framework that maps circuit-level parameters to a stochastic model of local oscillator phase noise in a radar array is developed. The model is used to analytically predict phase noise-induced sidelobes for a variety of radar configurations. The effects of range-Doppler-spatial processing are quantified and related to code-dependent parameters for FMCW and PMCW radars. Analytical expressions are verified with time-domain stochastic simulations, rigorously defined using the theory of stochastic differential equations. A link budget example for an automotive MIMO radar is provided, demonstrating the utility of the analytical framework in determining the required local oscillator phase noise for a desired radar dynamic range.", "doi": "10.1109/tcsi.2025.3526365", "issn": "1549-8328", "publisher": "IEEE", "publication": "IEEE Transactions on Circuits and Systems I: Regular Papers", "publication_date": "2025", "pages": "1-14" }, { "id": "authors:rtjvn-axy10", "collection": "authors", "collection_id": "rtjvn-axy10", "cite_using_url": "https://authors.library.caltech.edu/records/rtjvn-axy10", "type": "article", "title": "Wireless power transfer in space using flexible, lightweight, coherent arrays", "author": [ { "family_name": "Ayling", "given_name": "Alex", "orcid": "0009-0008-5440-7785", "clpid": "Ayling-Alex-E" }, { "family_name": "Fikes", "given_name": "Austin", "orcid": "0000-0003-4889-5782", "clpid": "Fikes-Austin-C" }, { "family_name": "Mizrahi", "given_name": "Oren S.", "orcid": "0000-0003-4271-8822", "clpid": "Mizrahi-Oren-S" }, { "family_name": "Wu", "given_name": "Ailec", "orcid": "0009-0008-7726-7842", "clpid": "Wu-Ailec" }, { "family_name": "Riazati", "given_name": "Raha", "orcid": "0009-0009-8544-8288" }, { "family_name": "Brunet", "given_name": "Jesse", "orcid": "0009-0002-8614-3362", "clpid": "Brunet-Jesse" }, { "family_name": "Abiri", "given_name": "Behrooz", "orcid": "0000-0002-3317-2752", "clpid": "Abiri-Behrooz" }, { "family_name": "Bohn", "given_name": "Florian", "orcid": "0000-0002-4619-378X", "clpid": "Bohn-Florian" }, { "family_name": "Gal-Katziri", "given_name": "Matan", "orcid": "0000-0001-9100-1188" }, { "family_name": "Hashemi", "given_name": "Mohammed Reza M.", "orcid": "0000-0002-8908-0048", "clpid": "Hashemi-Mohammed-R" }, { "family_name": "Padmanabhan", "given_name": "Sharmila", "orcid": "0000-0002-4579-7426" }, { "family_name": "Russell", "given_name": "Damon" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Space solar power (SSP), envisioned for decades as a solution for continuous, stable, and dynamically dispatchable clean energy, has seen tremendous interest and a number of experimental demonstrations in the last few years. A practical implementation has been elusive to date, owing to the high launch costs associated with heavy, rigid photovoltaic and wireless power transfer (WPT) arrays. Lightweight and flexible solutions for WPT have been demonstrated terrestrially but, to date, have not been deployed and tested in space. In this paper, we present an experimental space demonstration of a lightweight, flexible WPT array powered by custom radio-frequency integrated circuits. The transmit arrays, receive arrays, and the rest of the system were operated and tested for eight months in Low Earth Orbit (LEO). Results from these experiments, including pointing of the array’s beam to Earth and its detection by a ground station, are presented and discussed in detail. Observations and results from this mission uncover existing strengths and weaknesses that inform future steps towards realizing SSP.
", "doi": "10.1016/j.actaastro.2024.08.006", "issn": "0094-5765", "publisher": "Elsevier", "publication": "Acta Astronautica", "publication_date": "2024-11", "volume": "224", "pages": "226-243" }, { "id": "authors:gbhxy-z6j32", "collection": "authors", "collection_id": "gbhxy-z6j32", "cite_using_url": "https://authors.library.caltech.edu/records/gbhxy-z6j32", "type": "article", "title": "Visible spectrum waveguiding in bulk CMOS", "author": [ { "family_name": "Sarkar", "given_name": "Debjit", "orcid": "0000-0002-3066-9819", "clpid": "Sarkar-Debjit" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Waveguiding across the visible spectrum in an unmodified bulk CMOS chip is reported. The chip is fabricated in a standard CMOS process, and a simple wet etch removes metal in predetermined locations to expose glass rib waveguides. A modified Euler bend is introduced to improve bend radii by nearly an order of magnitude in the rib waveguides, and upper-bound losses are measured at visible wavelengths. These losses range from 6.2 dB/cm at 450 nm to 3.2 dB/cm at 650 nm and represent the lowest losses reported at visible wavelengths in unmodified bulk CMOS.", "doi": "10.1364/oe.502252", "issn": "1094-4087", "publisher": "Optica Publishing Group", "publication": "Optics Express", "publication_date": "2023-12-04", "series_number": "25", "volume": "31", "issue": "25", "pages": "42365-42372" }, { "id": "authors:r0r2c-wzz55", "collection": "authors", "collection_id": "r0r2c-wzz55", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20230404-448520900.2", "type": "article", "title": "A 28-GHz, Multi-Beam, Decentralized Relay Array", "author": [ { "family_name": "Nooshabadi", "given_name": "Samir", "orcid": "0000-0003-1645-0009", "clpid": "Nooshabadi-Samir" }, { "family_name": "Khial", "given_name": "Parham P.", "orcid": "0000-0002-3242-8541", "clpid": "Khial-Parham-P" }, { "family_name": "Fikes", "given_name": "Austin", "orcid": "0000-0003-4889-5782", "clpid": "Fikes-Austin" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Multi-beam relays can be used to overcome the non-line-of-sight (NLOS) issues in millimeter-wave (mm-wave) communication networks that serve many users in an obstruction-rich environment. We demonstrate a modular multi-beam relay array at 28 GHz, which is scalable and fully decentralized. The individual branches of the array are independent and do not need to share a timing reference or be physically located on the same substrate. Multi-beam capability is facilitated by a multi-channel baseband signal conditioning chain that includes a reconfigurable, passive, inductorless, 3rd-order N-path filter with programmable frequency-independent phase shift. This baseband signal conditioning chain enables beams concurrently multiplexed in spatial and frequency domains. We present the theory, design, and operation of the custom RFIC, which enables independent multi-beam relaying. Multiple RFICs are used to create relay arrays. A four-element relay array demonstrates three independently steered beams that utilize the full array aperture with a total wireless throughput of 625 Mb/s.", "doi": "10.1109/jssc.2023.3251898", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2023-05", "series_number": "5", "volume": "58", "issue": "5", "pages": "1212-1227" }, { "id": "authors:hqf4a-33j52", "collection": "authors", "collection_id": "hqf4a-33j52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220712-193859173", "type": "article", "title": "Large-Scale Crosstalk-Corrected Thermo-Optic Phase Shifter Arrays in Silicon Photonics", "author": [ { "family_name": "Gurses", "given_name": "B. Volkan", "orcid": "0000-0001-8184-208X", "clpid": "Gurses-B-Volkan" }, { "family_name": "Fatemi", "given_name": "Reza", "orcid": "0000-0001-9081-2608", "clpid": "Fatemi-Reza" }, { "family_name": "Khachaturian", "given_name": "Aroutin", "orcid": "0000-0001-8304-3302", "clpid": "Khachaturian-Aroutin" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "We introduce a thermo-optic phase shifter (TOPS) array architecture with independent phase control of each phase shifter for large-scale and high-density photonic integrated circuits with two different control schemes: pulse amplitude modulation (PAM) and pulse width modulation (PWM). We realize a compact spiral TOPS and a 288-element high-density row-column TOPS array with this architecture and drive TOPS with waveforms of both control schemes and of different array sizes. We present a thermal excitation model and a finite difference method-based simulation to simulate large-scale TOPS arrays and compare both schemes experimentally and theoretically. We also analyze the effects of thermal crosstalk in the realized TOPS array and implement a thermal crosstalk correction algorithm with the developed model. The high-density TOPS array architecture and the thermal crosstalk correction algorithm pave the way for high-density TOPS arrays with independent phase control in large-scale photonic integrated circuits interfaced with electronics limited in voltage swing and bandwidth.", "doi": "10.1109/JSTQE.2022.3189965", "issn": "1077-260X", "publisher": "IEEE", "publication": "IEEE Journal of Selected Topics in Quantum Electronics", "publication_date": "2022-11", "series_number": "6", "volume": "28", "issue": "6", "pages": "Art. No. 6101009" }, { "id": "authors:pwga6-esn60", "collection": "authors", "collection_id": "pwga6-esn60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20221024-123751900.4", "type": "article", "title": "Flexible active antenna arrays", "author": [ { "family_name": "Gal-Katziri", "given_name": "Matan", "orcid": "0000-0001-9100-1188", "clpid": "Gal-Katziri-M" }, { "family_name": "Fikes", "given_name": "Austin", "orcid": "0000-0003-4889-5782", "clpid": "Fikes-Austin" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Complex and dynamic control of radiated fields are advantageous for flexible radio systems, which naturally move, roll, bend, twist, deform, and vibrate. Practical challenges hinder the proliferation of these antenna arrays. This work shows how using radio-frequency microchips reduces system component count, decreases mass to ~0.1\u2009g cm\u207b\u00b2, and increases functionality and mechanical flexibility. We develop a general platform for large scale flexible arrays and demonstrate two different 256-elements, 30\u2009\u00d7\u200930\u2009cm\u00b2 flexible arrays. By varying supply distribution methods and radiators we show how performance can be optimized for maximum power delivery or physical flexibility. The demonstrated systems conform to curved surfaces with radii of curvatures as low as 23\u2009cm and wirelessly deliver\u2009~\u200980\u2009mW of DC power to a 6.7\u2009cm\u2009\u00d7\u200911\u2009cm-receiver over one meter away. This paves the way towards the integration of smart arrays in flexible wearables and deployable lightweight airborne systems.", "doi": "10.1038/s41528-022-00218-z", "issn": "2397-4621", "publisher": "Nature Publishing Group", "publication": "npj Flexible Electronics", "publication_date": "2022-10-14", "volume": "6", "pages": "Art. No. 85" }, { "id": "authors:k030e-vmy62", "collection": "authors", "collection_id": "k030e-vmy62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220121-11752000", "type": "article", "title": "Optically Synchronized Phased Arrays in CMOS", "author": [ { "family_name": "Gal-Katziri", "given_name": "Matan", "orcid": "0000-0001-9100-1188", "clpid": "Gal-Katziri-Matan" }, { "family_name": "Ives", "given_name": "Craig", "clpid": "Ives-Craig-E" }, { "family_name": "Khakpour", "given_name": "Armina", "clpid": "Khakpour-Armina" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Optical synchronization of large-span arrays offers significant benefits over electrical methods in terms of the weight, cost, power dissipation, and complexity of the clock distribution network. This work presents the analysis and design of the first phased array transmitter synchronized using a fully monolithic CMOS optical receiver. We demonstrate a bulk CMOS, 8-element, 28-GHz phased array building block with an on-chip photodiode (PD) that receives and processes the optical clock and uses an integrated PLL to generate eight independent phase-programmable RF outputs. The system demonstrates beam steering, data transmission, and remote synchronization of array elements at 28 GHz with fiber lengths up to 25 m, in order to show the scaling benefits of our approach. The provision of small footprint and cost-effective CMOS transceivers with integrated optoelectronic receivers enables exciting opportunities for low-cost and ultralight array systems.", "doi": "10.1109/jssc.2021.3136787", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2022-06", "series_number": "6", "volume": "57", "issue": "6", "pages": "1578-1593" }, { "id": "authors:2gnm1-e1692", "collection": "authors", "collection_id": "2gnm1-e1692", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220719-954621100", "type": "article", "title": "Discretization of annular-ring diffraction pattern for large-scale photonics beamforming", "author": [ { "family_name": "Khachaturian", "given_name": "Aroutin", "orcid": "0000-0001-8304-3302", "clpid": "Khachaturian-Aroutin" }, { "family_name": "Fatemi", "given_name": "Reza", "orcid": "0000-0001-9081-2608", "clpid": "Fatemi-Reza" }, { "family_name": "Darbinian", "given_name": "Artsroun", "clpid": "Darbinian-Artsroun" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A solid-state active beamformer based on the annular-ring diffraction pattern is demonstrated in an integrated photonic platform. Such a circularly symmetric annular-ring aperture achieves a radiating element limited field of view. Furthermore, it is demonstrated that a multi-annular-ring aperture with a fixed linear density of elements maintains the beam efficiency for larger apertures while reducing the beamwidth and side-lobe level. A 255-element multi-annular-ring optical phased array with active beamforming is implemented in a standard photonics process. A total of 510 phase and amplitude modulators enable beamforming and beam steering using this aperture. A row\u2013column drive methodology reduces the required electrical drivers by more than a factor of 5.", "doi": "10.1364/prj.443061", "issn": "2327-9125", "publisher": "Optica Publishing Group", "publication": "Photonics Research", "publication_date": "2022-05-01", "series_number": "5", "volume": "10", "issue": "5", "pages": "1177-1186" }, { "id": "authors:dqda3-kkd62", "collection": "authors", "collection_id": "dqda3-kkd62", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220727-412689800", "type": "article", "title": "Achieving full grating-lobe-free field of view with low-complexity co-prime photonic beamforming transceivers", "author": [ { "family_name": "Khachaturian", "given_name": "Aroutin", "orcid": "0000-0001-8304-3302", "clpid": "Khachaturian-Aroutin" }, { "family_name": "Fatemi", "given_name": "Reza", "orcid": "0000-0001-9081-2608", "clpid": "Fatemi-Reza" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Integrated photonic active beamforming can significantly reduce the size and cost of coherent imagers for LiDAR and medical imaging applications. In current architectures, the complexity of photonic and electronic circuitry linearly increases with the desired imaging resolution. We propose a novel photonic transceiver architecture based on co-prime sampling techniques that breaks this trade-off and achieves the full (radiating-element-limited) field of view (FOV) for a 2D aperture with a single-frequency laser. Using only order-of-N radiating elements, this architecture achieves beamwidth and sidelobe level (SLL) performance equivalent to a transceiver with order-of-N\u00b2 elements with half-wavelength spacing. Furthermore, we incorporate a pulse amplitude modulation (PAM) row\u2013column drive methodology to reduce the number of required electrical drivers for this architecture from order of N to order of \u221aN. A silicon photonics implementation of this architecture using two 64-element apertures, one for transmitting and one for receiving, requires only 34 PAM electrical drivers and achieves a transceiver SLL of \u221211.3\u2009dB with 1026 total resolvable spots, and 0.6\u00b0 beamwidth within a 23\u00b0\u00d716.3\u00b0 FOV.", "doi": "10.1364/prj.437518", "issn": "2327-9125", "publisher": "Optica Publishing Group", "publication": "Photonics Research", "publication_date": "2022-05", "series_number": "5", "volume": "10", "issue": "5", "pages": "A66-A73" }, { "id": "authors:7c5qy-6gj46", "collection": "authors", "collection_id": "7c5qy-6gj46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20220324-224059015", "type": "article", "title": "Foundry-fabricated grating coupler demultiplexer inverse-designed via fast integral methods", "author": [ { "family_name": "Sideris", "given_name": "Constantine", "orcid": "0000-0002-3042-4889", "clpid": "Sideris-Constantine" }, { "family_name": "Khachaturian", "given_name": "Aroutin", "orcid": "0000-0001-8304-3302", "clpid": "Khachaturian-Aroutin" }, { "family_name": "White", "given_name": "Alexander D.", "orcid": "0000-0002-5387-310X", "clpid": "White-Alexander-D" }, { "family_name": "Bruno", "given_name": "Oscar P.", "orcid": "0000-0001-8369-3014", "clpid": "Bruno-O-P" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Silicon photonics is an emerging technology which, enabling nanoscale manipulation of light on chips, impacts areas as diverse as communications, computing, and sensing. Wavelength division multiplexing is commonly used to maximize throughput over a single optical channel by modulating multiple data streams on different wavelengths concurrently. Traditionally, wavelength (de)multiplexers are implemented as monolithic devices, separate from the grating coupler, used to couple light into the chip. This paper describes the design and measurement of a grating coupler demultiplexer\u2014a single device which combines both light coupling and demultiplexing capabilities. The device was designed by means of a custom inverse design algorithm which leverages boundary integral Maxwell solvers of extremely rapid convergence as the mesh is refined. To the best of our knowledge, the fabricated device enjoys the lowest insertion loss reported for grating demultiplexers, small size, high splitting ratio, and low coupling-efficiency imbalance between ports, while meeting the fabricability constraints of a standard UV lithography process.", "doi": "10.1038/s42005-022-00839-w", "issn": "2399-3650", "publisher": "Nature Publishing Group", "publication": "Communications Physics", "publication_date": "2022-03-23", "volume": "5", "pages": "Art. No. 68" }, { "id": "authors:cfedq-42j80", "collection": "authors", "collection_id": "cfedq-42j80", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211104-153445242", "type": "article", "title": "A Framework for Array Shape Reconstruction Through Mutual Coupling", "author": [ { "family_name": "Fikes", "given_name": "Austin", "orcid": "0000-0003-4889-5782", "clpid": "Fikes-Austin" }, { "family_name": "Mizrahi", "given_name": "Oren S.", "orcid": "0000-0003-4271-8822", "clpid": "Mizrahi-Oren-S" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Flexible phased arrays potentially enable diverse applications not permitted by rigid systems; however, they introduce ambiguity in antenna element positions. If this position ambiguity can be overcome, flexible arrays can perform the full suite of array functions: beam steering, wavefront engineering, and beam focusing. Furthermore, shape reconstructions of arrays can be used for applications beyond beamforming. We propose a framework to reconstruct the shape of a flexible array that only uses mutual coupling measurements and does not require additional sensors or functionalities in the system. We discuss the approach, a two-step algorithm, which is highly modular and can be implemented in a variety of phased array systems. To demonstrate the accuracy of the approach, we present results from two passive 2.5-GHz phased array setups using dipole and patch antennas, as well as a 10-GHz (active) integrated circuit flexible phased array, and demonstrate the accuracy of the approach in this system. In all cases, the algorithm reconstructs the antenna shape accurately, with average position errors of approximately 6% of the wavelength. This article can serve as the beginning of the broad study of shape reconstruction algorithms and their applications.", "doi": "10.1109/tmtt.2021.3097729", "issn": "0018-9480", "publisher": "Institute of Electrical and Electronics Engineers", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2021-10", "series_number": "10", "volume": "69", "issue": "10", "pages": "4422-4436" }, { "id": "authors:cd6sp-5ek98", "collection": "authors", "collection_id": "cd6sp-5ek98", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20211217-98205000", "type": "article", "title": "IQ Photonic Receiver for Coherent Imaging With a Scalable Aperture", "author": [ { "family_name": "Khachaturian", "given_name": "Aroutin", "orcid": "0000-0001-8304-3302", "clpid": "Khachaturian-Aroutin" }, { "family_name": "Fatemi", "given_name": "Reza", "orcid": "0000-0001-9081-2608", "clpid": "Fatemi-Reza" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Silicon photonics (SiP) integrated coherent image sensors offer higher sensitivity and improved range-resolution-product compared to direct detection image sensors such as CCD and CMOS devices. Previous generations of SiP coherent imagers suffer from relative optical phase fluctuations between the signal and reference paths, which results in random phase and amplitude fluctuations in the output signal. This limitation negatively impacts the SNR and signal acquisition times. Here, we present a coherent imager system that suppresses the optical carrier signal and removes non-idealities from the relative optical path using a photonic in-phase (I) and quadrature (Q) receiver via a 90\u00b0 hybrid detector. Furthermore, we incorporate row-column read-out and row-column addressing schemes to address the electro-optical interconnect density challenge. Our novel row-column read-out architecture for the sensor array requires only 2N interconnects for N\u00b2 sensors. An 8\u00d78 IQ sensor array is presented as a proof-of-concept demonstration with 1.2\u00d710\u207b\u2075 resolution over range accuracy. Free-space FMCW ranging with 250\u03bcm resolution at 1 m distance has been demonstrated using this sensor array.", "doi": "10.1109/ojsscs.2021.3113264", "issn": "2644-1349", "publisher": "Institute of Electrical and Electronics Engineers", "publication": "IEEE Open Journal of the Solid-State Circuits Society", "publication_date": "2021-09-17", "volume": "1", "pages": "263-270" }, { "id": "authors:6zjk5-1nj75", "collection": "authors", "collection_id": "6zjk5-1nj75", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201215-141035798", "type": "article", "title": "Dynamic Focusing of Large Arrays for Wireless Power Transfer and Beyond", "author": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Abiri", "given_name": "Behrooz", "orcid": "0000-0002-3317-2752", "clpid": "Abiri-Behrooz" }, { "family_name": "Bohn", "given_name": "Florian", "orcid": "0000-0002-4619-378X", "clpid": "Bohn-Florian" }, { "family_name": "Gal-Katziri", "given_name": "Matan", "orcid": "0000-0001-9100-1188", "clpid": "Gal-Katziri-Matan" }, { "family_name": "Manohara", "given_name": "Mohith H.", "orcid": "0000-0003-1180-8470", "clpid": "Manohara-Mohith-H" } ], "abstract": "We present architectures, circuits, and algorithms for dynamic 3-D lensing and focusing of electromagnetic power in radiative near- and far-field regions by arrays that can be arbitrary and nonuniform. They can benefit applications such as wireless power transfer at a distance (WPT-AD), volumetric sensing and imaging, high-throughput communications, and optical phased arrays. Theoretical limits on system performance are calculated. An adaptive algorithm focuses the power at the receiver(s) without prior knowledge of its location(s). It uses orthogonal bases to change the phases of multiple elements simultaneously to enhance the dynamic range. One class of such 2-D orthogonal and pseudo-orthogonal masks is constructed using the Hadamard and pseudo-Hadamard matrices. Generation and recovery units (GU and RU) work collaboratively to focus energy quickly and reliably with no need for factory calibration. Orthogonality enables batch processing in high-latency and low-rate communication settings. Secondary vector-based calculations allow instantaneous refocusing at different locations using element-wise calculations. An emulator enables further evaluation of the system. We demonstrate modular WPT-AD GUs of up to 400 elements utilizing arrays of 65-nm CMOS ICs to focus power on RUs that convert the RF power to dc. Each RFIC synthesizes 16 independently phase-controlled RF outputs around 10 GHz from a common single low-frequency reference. Detailed measurements demonstrate the feasibility and effectiveness of RF lensing techniques presented in this article. More than 2 W of dc power can be recovered through a wireless transfer at distances greater than 1 m. The system can dynamically project power at various angles and at distances greater than 10 m. These developments are another step toward unified wireless power, sensing, and communication solutions in the future.", "doi": "10.1109/JSSC.2020.3036895", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2021-07", "series_number": "7", "volume": "56", "issue": "7", "pages": "2077-2101" }, { "id": "authors:6k6e0-prt13", "collection": "authors", "collection_id": "6k6e0-prt13", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210113-163505538", "type": "article", "title": "Programmable Active Mirror: A Scalable Decentralized Router", "author": [ { "family_name": "Fikes", "given_name": "Austin", "orcid": "0000-0003-4889-5782", "clpid": "Fikes-Austin" }, { "family_name": "Khial", "given_name": "Parham P.", "orcid": "0000-0002-3242-8541", "clpid": "Khial-Parham-P" }, { "family_name": "Nooshabadi", "given_name": "Samir", "clpid": "Nooshabadi-Samir" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "This work proposes and demonstrates the scalable router array that eliminates the internal centralization of conventional arrays, unlocking scalability, and the potential for a system composed of spatially separated elements that do not share a common timing reference. Architectural variations are presented, and their specific tradeoffs are discussed. The general operation, steering capabilities, signal and noise considerations, and timing control advantages are evaluated through analysis, simulation, and measurements. An element-level CMOS radio frequency integrated circuit (RFIC) is developed and used to demonstrate a four-element 25 GHz prototype router. The RFIC's programmable true time delay (TTD) control is used to correct path-length-difference-induced intersymbol interference (ISI) and improve a rerouted 270-Mb/s 64-QAM constellation from a completely scrambled state to an EVM of 4% rms (\u221228 dB). The prototype scalable router's concurrent dual-beam capabilities are demonstrated by simultaneously steering two full power beams at 24.9 and 25 GHz in two different directions in a free-space electromagnetic setup.", "doi": "10.1109/tmtt.2020.3042516", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2021-03", "series_number": "3", "volume": "69", "issue": "3", "pages": "1860-1874" }, { "id": "authors:fgyxk-ff673", "collection": "authors", "collection_id": "fgyxk-ff673", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20210211-102546915", "type": "article", "title": "Subtractive photonics", "author": [ { "family_name": "Fatemi", "given_name": "Reza", "orcid": "0000-0001-9081-2608", "clpid": "Fatemi-Reza" }, { "family_name": "Ives", "given_name": "Craig", "clpid": "Ives-Craig-E" }, { "family_name": "Khachaturian", "given_name": "Aroutin", "orcid": "0000-0001-8304-3302", "clpid": "Khachaturian-Aroutin" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Realization of a multilayer photonic process, as well as co-integration of a large number of photonic and electronic components on a single substrate, presents many advantages over conventional solutions and opens a pathway for various novel architectures and applications. Despite the many potential advantages, realization of a complex multilayer photonic process compatible with low-cost CMOS platforms remains challenging. In this paper, a photonic platform is investigated that uses subtractively manufactured structures to fabricate such systems. These structures are created solely using simple post-processing methods, with no modification to the foundry process. This method uses the well-controlled metal layers of advanced integrated electronics as sacrificial layers to define dielectric shapes as optical components. Metal patterns are removed using an etching process, leaving behind a complex multilayer photonic system, while keeping the electronics'metal wiring intact. This approach can be applied to any integrated chip with well-defined metallization, including those produced in pure electronics processes, pure photonics processes, heterogeneously integrated processes, monolithic electronic-photonic processes, etc. This paper provides a proof-of-concept example of monolithic electronic-photonic integration in a 65\u2009nm bulk CMOS process and demonstrates proof-of-concept photonic structures. The fabrication results, characterization, and measurement data are presented.", "doi": "10.1364/oe.410139", "issn": "1094-4087", "publisher": "Optical Society of America", "publication": "Optics Express", "publication_date": "2021-01-18", "series_number": "2", "volume": "29", "issue": "2", "pages": "877-893" }, { "id": "authors:ecawf-37x45", "collection": "authors", "collection_id": "ecawf-37x45", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20201002-151459041", "type": "article", "title": "Breaking FOV-Aperture Trade-Off with Multi-Mode Nano-Photonic Antennas", "author": [ { "family_name": "Fatemi", "given_name": "Reza", "orcid": "0000-0001-9081-2608", "clpid": "Fatemi-R" }, { "family_name": "Khial", "given_name": "Parham P.", "orcid": "0000-0002-3242-8541", "clpid": "Khial-P-P" }, { "family_name": "Khachaturian", "given_name": "Aroutin", "orcid": "0000-0001-8304-3302", "clpid": "Khachaturian-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Nano-photonic antennas are one of the key components in integrated photonic transmitter and receiver systems. Conventionally, grating couplers, designed to couple into an optical fiber, suffering from limitations such as large footprint and small field-of-view (FOV) have been used as on-chip antennas. The challenge of the antenna design is more pronounced for the receiver systems, where both the collected power by the antenna and its FOV often need to be maximized. While some novel solutions have been demonstrated recently, identifying fundamental limits and trade-offs in nano-photonic antenna design is essential for devising compact antenna structures with improved performance. In this paper, the fundamental electromagnetic limits, as well as fabrication imposed constraints on improving antenna effective aperture and FOV are studied, and approximated performance upper limits are derived and quantified. By deviating from the conventional assumptions leading to these limits, high-performance multi-mode antenna structures with performance characteristics beyond the conventional perceived limits are demonstrated. Finally, the application of a pillar multi-mode antenna in a dense array is discussed, an antenna array with more than 95% collection efficiency and 170\u2218 FOV is demonstrated, and a coherent receiving system utilizing such an aperture is presented.", "doi": "10.1109/jstqe.2020.3026966", "issn": "1077-260X", "publisher": "IEEE", "publication": "IEEE Journal of Selected Topics in Quantum Electronics", "publication_date": "2021-01", "series_number": "1", "volume": "27", "issue": "1", "pages": "Art. No. 6100614" }, { "id": "authors:6sjsf-rw152", "collection": "authors", "collection_id": "6sjsf-rw152", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200528-104303291", "type": "article", "title": "Dynamically Programmable Magnetic Fields for Controlled Movement of Cells Loaded with Iron Oxide Nanoparticles", "author": [ { "family_name": "Pai", "given_name": "Alex", "clpid": "Pai-Alex" }, { "family_name": "Cao", "given_name": "Pengpeng", "clpid": "Cao-Pengpeng" }, { "family_name": "White", "given_name": "Ethan E.", "clpid": "White-E-E" }, { "family_name": "Hong", "given_name": "Brian", "orcid": "0000-0001-8099-0312", "clpid": "Hong-Brian" }, { "family_name": "Pailevanian", "given_name": "Torkom", "clpid": "Pailevanian-T" }, { "family_name": "Wang", "given_name": "Michelle", "clpid": "Wang-Michelle" }, { "family_name": "Badie", "given_name": "Behnam", "clpid": "Badie-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Berlin", "given_name": "Jacob M.", "orcid": "0000-0001-7498-766X", "clpid": "Berlin-J-M" } ], "abstract": "Cell-based therapies are becoming increasingly prominent in numerous medical contexts, particularly in regenerative medicine and the treatment of cancer. However, since the efficacy of the therapy is largely dependent on the concentration of therapeutic cells at the treatment area, a major challenge associated with cell-based therapies is the ability to move and localize therapeutic cells within the body. In this article, a technique based on dynamically programmable magnetic fields is successfully demonstrated to noninvasively aggregate therapeutic cells at a desired location. Various types of therapeutically relevant cells (neural stem cells, monocytes/macrophages, and chimeric antigen receptor T cells) are loaded with iron oxide nanoparticles and then focused at a particular site using externally controlled electromagnets. These experimental results serve as a readily scalable prototype for designing an apparatus that patients can wear to focus therapeutic cells at the anatomical sites needed for treatment.", "doi": "10.1021/acsabm.0c00226", "issn": "2576-6422", "publisher": "American Chemical Society", "publication": "ACS Applied Bio Materials", "publication_date": "2020-07-20", "series_number": "7", "volume": "3", "issue": "7", "pages": "4139-4147" }, { "id": "authors:dtden-pmq53", "collection": "authors", "collection_id": "dtden-pmq53", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200402-141913396", "type": "article", "title": "An mm-Wave CMOS I-Q Subharmonic Resistive Mixer for Wideband Zero-IF Receivers", "author": [ { "family_name": "Parveg", "given_name": "Dristy", "orcid": "0000-0002-9166-8764", "clpid": "Parveg-D" }, { "family_name": "Varonen", "given_name": "Mikko", "orcid": "0000-0002-6515-5092", "clpid": "Varonen-M" }, { "family_name": "Safaripour", "given_name": "Amirreza", "orcid": "0000-0001-9758-6156", "clpid": "Safaripour-A" }, { "family_name": "Kangaslahti", "given_name": "Pekka", "clpid": "Kangaslahti-P" }, { "family_name": "Kantanen", "given_name": "Mikko", "clpid": "Kantanen-M" }, { "family_name": "Tikka", "given_name": "Tero", "clpid": "Tikka-T" }, { "family_name": "Gaier", "given_name": "Todd", "clpid": "Gaier-T" }, { "family_name": "Halonen", "given_name": "Kari A. I.", "clpid": "Halonen-K-A-I" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "In this letter, we propose a novel wideband subharmonically pumped fully differential I\u2013Q resistive mixer architecture, which eliminates the necessity for on-chip dc-blocking capacitors to integrate IF amplifiers. The proposed differential subharmonic mixer topology is verified by presenting a CMOS millimeter-wave monolithic integrated circuit (MMIC), which includes the mixer and two on-chip differential IF amplifiers at the mixer's I- and Q-channels. The 3-dB IF frequency bandwidth is measured from 0.01 to 5 GHz with a peak conversion gain (CG) of \u22122 dB and an image rejection ratio (IRR) of more than 25 dB over the IF frequency range. The proposed mixer covers the input signal (RF) frequency from 170 to 185 GHz. The mixer has also been tested with an on-chip voltage-controlled oscillator (VCO) and shows \u22124.7-dB CG with a 3-dB IF bandwidth from 0.01 to 4.5 GHz.", "doi": "10.1109/lmwc.2020.2980973", "issn": "1531-1309", "publisher": "IEEE", "publication": "IEEE Microwave and Wireless Components Letters", "publication_date": "2020-05", "series_number": "5", "volume": "30", "issue": "5", "pages": "520-523" }, { "id": "authors:9tjrk-xgy56", "collection": "authors", "collection_id": "9tjrk-xgy56", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20200212-111715644", "type": "article", "title": "A Silicon Photonics Computational Lensless Active-Flat-Optics Imaging System", "author": [ { "family_name": "White", "given_name": "Alexander", "orcid": "0000-0002-5387-310X", "clpid": "White-A-D" }, { "family_name": "Khial", "given_name": "Parham", "orcid": "0000-0002-3242-8541", "clpid": "Khial-P-P" }, { "family_name": "Salehi", "given_name": "Fariborz", "clpid": "Salehi-F" }, { "family_name": "Hassibi", "given_name": "Babak", "orcid": "0000-0002-1375-5838", "clpid": "Hassibi-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "The need for lightweight, miniature imaging systems is becoming increasingly prevalent in light of the development of wearable electronics, IoT devices, and drones. Computational imaging enables new types of imaging systems that replace standard optical components like lenses with cleverly designed computational processes. Traditionally, many of these types of systems use conventional complementary metal oxide semiconductor (CMOS) or charge coupled device (CCD) sensors for data collection. While this allows for rapid development of large-scale systems, the lack of system-sensor co-design limits the compactness and performance. Here we propose integrated photonics as a candidate platform for the implementation of such co-integrated systems. Using grating couplers and co-designed computational processing in lieu of a lens, we demonstrate the use of silicon photonics as a viable platform for computational imaging with a prototype lensless imaging device. The proof-of-concept device has 20 sensors and a 45-degree field of view, and its optics and sensors are contained within a 2,000 \u03bcm \u00d7 200 \u03bcm \u00d7 20 \u03bcm volume.", "doi": "10.1038/s41598-020-58027-1", "pmcid": "PMC6997425", "issn": "2045-2322", "publisher": "Nature Publishing Group", "publication": "Scientific Reports", "publication_date": "2020-02-03", "volume": "10", "pages": "Art. No. 1689" }, { "id": "authors:kdfym-b3b02", "collection": "authors", "collection_id": "kdfym-b3b02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190926-144327410", "type": "article", "title": "Computational aberration correction of VIS-NIR multispectral imaging microscopy based on Fourier ptychography", "author": [ { "family_name": "Shen", "given_name": "Cheng", "orcid": "0000-0001-7136-4715", "clpid": "Shen-Cheng" }, { "family_name": "Chan", "given_name": "Antony Chi Shing", "clpid": "Chan-Antony-Chi-Shing" }, { "family_name": "Chung", "given_name": "Jaebum", "orcid": "0000-0003-3932-8428", "clpid": "Chung-Jaebum" }, { "family_name": "Williams", "given_name": "D. Elliott", "clpid": "Williams-D-E" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Yang", "given_name": "Changhuei", "orcid": "0000-0001-8791-0354", "clpid": "Yang-Changhuei" } ], "abstract": "Due to the chromatic dispersion properties inherent in all optical materials, even the best-designed multispectral objective will exhibit residual chromatic aberration. Here, we demonstrate a multispectral microscope with a computational scheme based on the Fourier ptychographic microscopy (FPM) to correct these effects in order to render undistorted, in-focus images. The microscope consists of 4 spectral channels ranging from 405 nm to 1552 nm. After the computational aberration correction, it can achieve isotropic resolution enhancement as verified with the Siemens star sample. We image a flip-chip to show the promise of our system to conduct fault detection on silicon chips. This computational approach provides a cost-efficient strategy for high quality multispectral imaging over a broad spectral range.", "doi": "10.1364/oe.27.024923", "issn": "1094-4087", "publisher": "Optical Society of America", "publication": "Optics Express", "publication_date": "2019-09-02", "series_number": "18", "volume": "27", "issue": "18", "pages": "24923-24937" }, { "id": "authors:b0yg2-18986", "collection": "authors", "collection_id": "b0yg2-18986", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190814-152418722", "type": "article", "title": "Proximal-Field Sensing: In Situ Prediction of Far-Field Radiation for Integrated Radiators", "author": [ { "family_name": "Safaripour", "given_name": "Amirreza", "orcid": "0000-0001-9758-6156", "clpid": "Safaripour-A" }, { "family_name": "Asghari", "given_name": "Bahar", "clpid": "Asghari-B" }, { "family_name": "Hashemi", "given_name": "Mohammed Reza M.", "orcid": "0000-0002-8908-0048", "clpid": "Hashemi-M-R-M" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Proximal-field sensing is introduced as an integrated sensing scheme for the in situ characterization of far-field radiation properties of integrated radiators, and the proximal-field radiation sensors (PFRSs) are proposed as the tools to enable this capability. These sensors are integrated on the same dielectric substrate as the transmitting antennas and extract the existing information in the excited substrate modes and use it to predict the far-field radiation properties in real time based on in situ field measurements in the close proximity of the transmitting antennas, without any need to use additional test equipment, remove the antenna from its operating environment, or interrupt its operation in a wireless system. The functionality of this sensing scheme is verified on both PCB and IC platforms through the implementation of two proof-of-concept prototypes, and different aspects of the electromagnetic and electronic design of the PFRS integration with integrated radiators are investigated.", "doi": "10.1109/tmtt.2019.2929154", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2019-09", "series_number": "9", "volume": "67", "issue": "9", "pages": "3743-3756" }, { "id": "authors:5gka5-51e69", "collection": "authors", "collection_id": "5gka5-51e69", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190711-133035819", "type": "article", "title": "A General Theory of Injection Locking and Pulling in Electrical Oscillators--Part II: Amplitude Modulation in LC Oscillators, Transient Behavior, and Frequency Division", "author": [ { "family_name": "Hong", "given_name": "Brian", "orcid": "0000-0001-8099-0312", "clpid": "Hong-Brian" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A number of specialized topics within the theory of injection locking and pulling are addressed. The material builds on our impulse sensitivity function (ISF)-based, time-synchronous model of electrical oscillators under the influence of a periodic injection. First, we show how the accuracy of this model for LC oscillators under large injection is greatly enhanced by accounting for the injection's effect on the oscillation amplitude. In doing so, we capture the asymmetry of the lock range as well as the distinct behaviors exhibited by different LC oscillator topologies. Existing LC oscillator injection locking and pulling theories in the literature are subsumed as special cases. Next, a transient analysis of the dynamics of injection pulling is carried out, both within and outside of the lock range. Finally, we show how our existing framework naturally accommodates locking onto superharmonic and subharmonic injections, leading to several design considerations for injection-locked frequency dividers (ILFDs) and the implementation of a low-power dual-modulus prescaler from an injection-locked ring oscillator. Our theoretical conclusions are supported by simulations and experimental data from a variety of LC, ring, and relaxation oscillators.", "doi": "10.1109/jssc.2019.2908763", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2019-08", "series_number": "8", "volume": "54", "issue": "8", "pages": "2122-2139" }, { "id": "authors:beeyt-tfj40", "collection": "authors", "collection_id": "beeyt-tfj40", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190709-133258992", "type": "article", "title": "A General Theory of Injection Locking and Pulling in Electrical Oscillators--Part I: Time-Synchronous Modeling and Injection Waveform Design", "author": [ { "family_name": "Hong", "given_name": "Brian", "orcid": "0000-0001-8099-0312", "clpid": "Hong-Brian" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A general model of electrical oscillators under the influence of a periodic injection is presented. Stemming solely from the autonomy and periodic time variance inherent in all oscillators, the model's underlying approach makes no assumptions about the topology of the oscillator or the shape of the injection waveform. A single first-order differential equation is shown to be capable of predicting a number of important properties, including the lock range, the relative phase of an injection-locked oscillator, and mode stability. The framework also reveals how the injection waveform can be designed to optimize the lock range. A diverse collection of simulations and measurements, performed on various types of oscillators, serve to verify the proposed theory.", "doi": "10.1109/jssc.2019.2908753", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2019-08", "series_number": "8", "volume": "54", "issue": "8", "pages": "2109-2121" }, { "id": "authors:z3p1g-rzw92", "collection": "authors", "collection_id": "z3p1g-rzw92", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190718-133623700", "type": "article", "title": "Analysis and Design of Coupled Inductive Bridges for Magnetic Sensing Applications", "author": [ { "family_name": "Gal-Katziri", "given_name": "Matan", "orcid": "0000-0001-9100-1188", "clpid": "Gal-Katziri-M" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "This paper presents the analysis and design of a novel magnetic sensor. We study the underlying physics of inductance shift sensors as a special case of the broader family of magnetic energy deviation sensors. The result is a quantitative definition of performance metrics with all assumptions and approximations explicitly stated. This analysis is then used to design a modified ac Wheatstone bridge that uses two inductor-pairs in a cross-coupled configuration, to half its size and double its transducer gain while maintaining a fully differential structure with a matched frequency response. A proof-of-concept sensor was fabricated with peripheral circuitry in a 65-nm bulk CMOS process to operate between 770 and 1450 MHz with an effective sensing area of 200 \u00b5m x 200 \u00b5m. The new bridge sensor is fully characterized at a frequency of 770 MHz and demonstrates a reliable and continuous detection of 4.5-\u00b5m iron-oxide magnetic beads over time periods longer than 30 min, appreciably longer than previously reported works.", "doi": "10.1109/jssc.2019.2907196", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2019-07", "series_number": "7", "volume": "54", "issue": "7", "pages": "1883-1894" }, { "id": "authors:tjhsy-mxr73", "collection": "authors", "collection_id": "tjhsy-mxr73", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190228-152237706", "type": "article", "title": "A Nonuniform Sparse 2-D Large-FOV Optical Phased Array With a Low-Power PWM Drive", "author": [ { "family_name": "Fatemi", "given_name": "Reza", "orcid": "0000-0001-9081-2608", "clpid": "Fatemi-R" }, { "family_name": "Khachaturian", "given_name": "Aroutin", "orcid": "0000-0001-8304-3302", "clpid": "Khachaturian-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Integrated optical phased arrays (OPAs) capable of adaptive beamforming and beam steering enable a wide range of applications. For many of these applications, a large scale 2-D OPA with full phase control for each radiating element is essential to achieve a functional low-cost solution. However, the scalability of such OPAs has been hampered by the optical feed distribution difficulties in a planar photonics process, as well as the high power consumption associated with having a large number of phase control units. In this paper, we present a two-chip solution low-power scalable OPA with a nonuniform sparse aperture, providing radiation pattern adjustment and feed distribution feasibility in a CMOS compatible silicon photonics process. The demonstrated OPA with a 128-element aperture achieves the highest reported grating-lobe-free field-of-view (FOV)-to-beamwidth ratio of 16\u00b0/0.8\u00b0, which is equivalent to a 484-element uniform array. This translates to at least 400 resolvable spots, 30 times more than the state-of-the-art 2-D OPAs. Moreover, by utilizing compact phase shifters in a row\u2013column power delivery grid, we reduce the number of required drivers from 144 to 37. A high-swing pulsewidth modulation (PWM) driving circuit featuring breakdown voltage multipliers and soft turn-on activation significantly reduces the power consumption of the system. The electronic driver chip and the integrated photonic chip are fabricated on a 65-nm CMOS process and a thick silicon-on-insulator (SOI) silicon photonics process, occupying 1.7 mm^2 and 2.08 mm^2 of active area, respectively.", "doi": "10.1109/jssc.2019.2896767", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2019-05", "series_number": "5", "volume": "54", "issue": "5", "pages": "1200-1215" }, { "id": "authors:aprqe-vd583", "collection": "authors", "collection_id": "aprqe-vd583", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190416-120325923", "type": "article", "title": "A flexible phased array system with low areal mass density", "author": [ { "family_name": "Hashemi", "given_name": "Mohammed Reza M.", "orcid": "0000-0002-8908-0048", "clpid": "Hashemi-M-R-M" }, { "family_name": "Fikes", "given_name": "Austin C.", "clpid": "Fikes-A-C" }, { "family_name": "Gal-Katziri", "given_name": "Matan", "orcid": "0000-0001-9100-1188", "clpid": "Gal-Katziri-M" }, { "family_name": "Abiri", "given_name": "Behrooz", "orcid": "0000-0002-3317-2752", "clpid": "Abiri-B" }, { "family_name": "Bohn", "given_name": "Florian", "clpid": "Bohn-F" }, { "family_name": "Safaripour", "given_name": "Amirreza", "orcid": "0000-0001-9758-6156", "clpid": "Safaripour-A" }, { "family_name": "Kelzenberg", "given_name": "Michael D.", "orcid": "0000-0002-6249-2827", "clpid": "Kelzenberg-M-D" }, { "family_name": "Warmann", "given_name": "Emily L.", "clpid": "Warmann-E-L" }, { "family_name": "Espinet", "given_name": "Pilar", "orcid": "0000-0002-7656-0077", "clpid": "Espinet-Gonz\u00e1lez-P" }, { "family_name": "Vaidya", "given_name": "Nina", "clpid": "Vaidya-N" }, { "family_name": "Gdoutos", "given_name": "Eleftherios E.", "clpid": "Gdoutos-E-E" }, { "family_name": "Leclerc", "given_name": "Christophe", "clpid": "Leclerc-C" }, { "family_name": "Royer", "given_name": "Fabien", "clpid": "Royer-F" }, { "family_name": "Pellegrino", "given_name": "Sergio", "orcid": "0000-0001-9373-3278", "clpid": "Pellegrino-S" }, { "family_name": "Atwater", "given_name": "Harry A.", "orcid": "0000-0001-9435-0201", "clpid": "Atwater-H-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Phased arrays are multiple antenna systems capable of forming and steering beams electronically using constructive and destructive interference between sources. They are employed extensively in radar and communication systems but are typically rigid, bulky and heavy, which limits their use in compact or portable devices and systems. Here, we report a scalable phased array system that is both lightweight and flexible. The array architecture consists of a self-monitoring complementary metal\u2013oxide\u2013semiconductor-based integrated circuit, which is responsible for generating multiple independent phase- and amplitude-controlled signal channels, combined with flexible and collapsible radiating structures. The modular platform, which can be collapsed, rolled and folded, is capable of operating standalone or as a subarray in a larger-scale flexible phased array system. To illustrate the capabilities of the approach, we created a 4\u2009\u00d7\u20094 flexible phased array tile operating at 9.4\u201310.4\u2009GHz, with a low areal mass density of 0.1\u2009g\u2009cm^(\u22122). We also created a flexible phased array prototype that is powered by photovoltaic cells and intended for use in a wireless space-based solar power transfer array.", "doi": "10.1038/s41928-019-0247-9", "issn": "2520-1131", "publisher": "Nature Publishing Group", "publication": "Nature Electronics", "publication_date": "2019-05", "series_number": "5", "volume": "2", "issue": "5", "pages": "195-205" }, { "id": "authors:6ajep-t6t43", "collection": "authors", "collection_id": "6ajep-t6t43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20190102-155139163", "type": "article", "title": "A Phasor-Based Analysis of Sinusoidal Injection Locking in LC and Ring Oscillators", "author": [ { "family_name": "Hong", "given_name": "Brian", "orcid": "0000-0001-8099-0312", "clpid": "Hong-Brian" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A new perspective into the locking behavior of LC and ring oscillators is presented. By decomposing a sinusoidal injection current into in-phase and quadrature-phase components, exact expressions for the amplitude and phase of an injection-locked LC oscillator which hold for any injection strength and frequency are derived and confirmed by simulation. The analysis, which can be naturally extended to an arbitrary LC resonator topology, leads to a rigorous understanding of the fundamental physics underlying the locking phenomenon. Furthermore, an investigation of the different necessary and sufficient conditions for injection locking to occur is carried out, leading to a more precise notion of the lock range. The ring oscillator is also analyzed in an analogous fashion, resulting in simple yet accurate closed-form expressions for the fractional lock range in the small-injection and long-ring regimes; the expressions are validated by simulations of single-ended inverter-based ring oscillators in 65-nm CMOS. The mathematics behind how the injection modifies the phase delay contributed by each stage in the ring is discussed. A corollary that generalizes the small-injection lock range to any feedback-based oscillator topology is established. Conceptual and analytical connections to the existing literature are reviewed.", "doi": "10.1109/tcsi.2018.2860045", "issn": "1549-8328", "publisher": "IEEE", "publication": "IEEE Transactions on Circuits and Systems I: Regular Papers", "publication_date": "2019-01", "series_number": "1", "volume": "66", "issue": "1", "pages": "355-368" }, { "id": "authors:1qvfa-4vr18", "collection": "authors", "collection_id": "1qvfa-4vr18", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181205-145145663", "type": "article", "title": "High sensitivity active flat optics optical phased array receiver with a two-dimensional aperture", "author": [ { "family_name": "Fatemi", "given_name": "Reza", "orcid": "0000-0001-9081-2608", "clpid": "Fatemi-R" }, { "family_name": "Abiri", "given_name": "Behrooz", "orcid": "0000-0002-3317-2752", "clpid": "Abiri-B" }, { "family_name": "Khachaturian", "given_name": "Aroutin", "orcid": "0000-0001-8304-3302", "clpid": "Khachaturian-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Optical phased arrays (OPAs) on integrated photonic platforms provide a low-cost chip-scale solution for many applications. Despite the numerous demonstrations of OPA transmitters, the realization of a functional OPA receiver presents a challenge due to the low received signal level in the presence of noise and interference that necessitates high sensitivity of the receiver. In this paper, an integrated receiver system is presented that is capable of on-chip adaptive manipulation and processing of the captured waveform. The receiver includes an optoelectronic mixer that down-converts optical signals to radio frequencies while maintaining their phase and amplitude information. The optoelectronic mixer also provides conversion gain that enhances the system sensitivity and its robustness to noise and interference. Using this system, the first OPA receiver with a two-dimensional aperture of 8-by-8 receiving elements is demonstrated which can selectively receive light from 64 different angles. The OPA receiver can form reception beams with a beamwidth of 0.75\u00b0 over an 8\u00b0 grating-lobe-free field of view.", "doi": "10.1364/oe.26.029983", "issn": "1094-4087", "publisher": "Optical Society of America", "publication": "Optics Express", "publication_date": "2018-11-12", "series_number": "23", "volume": "26", "issue": "23", "pages": "29983-29999" }, { "id": "authors:y6sdp-58y27", "collection": "authors", "collection_id": "y6sdp-58y27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20181023-151906461", "type": "article", "title": "Design and Implementation of Reference-Free Drift-Cancelling CMOS Magnetic Sensors for Biosensing Applications", "author": [ { "family_name": "Sideris", "given_name": "Constantine", "orcid": "0000-0002-3042-4889", "clpid": "Sideris-C" }, { "family_name": "Khial", "given_name": "Parham P.", "orcid": "0000-0002-3242-8541", "clpid": "Khial-P-P" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Magnetic imagers, which utilize magnetic nanoparticles as labels to realize biodetection assays, hold significant promise for deployment at the point-of-use. Resonance-shift-based sensors can be realized in standard CMOS processes without post-process modifications and offer great sensitivity at low price tags. Unfortunately, CMOS resonant-shift magnetic sensors suffer significant degradation in SNR and long-term stability due to low on-chip inductor quality factors and significant noise introduced from active devices and thermal variations. This makes standard resonant-shift-based imagers undesirable for use in low-signal biodetection assays. Furthermore, and most importantly, the significant long-term drift due to slow-varying noise sources and temperature changes makes these sensors inadequate for bioexperiments which may take timescales on the order of hours to reach completion. In this paper, we propose a transformer-based approach which enables sub-parts-per-million (PPM) signal detection without the need for any thermal compensation. The approach is self-referencing, leading to significant savings in chip area by removing the need for replica reference cells. We analyze the performance of the transformer-based circuit compared to the original second-order system and demonstrate its superiority for rejecting system noise. A proof-of-concept design of a fully integrated 2\u00d72 CMOS transformer-based magnetic sensor array is presented which achieves reference-free, sub-PPM detection of magnetic signals. The system can be powered and operated completely from a laptop USB interface and each sensing cell can consume less than 3 mW of DC power. Finally, we show the results of an initial DNA biodetection experiment which confirms the capability of the sensor to be used for realistic bioassays.", "doi": "10.1109/JSSC.2018.2865480", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2018-11", "series_number": "11", "volume": "53", "issue": "11", "pages": "3065-3075" }, { "id": "authors:k0gn4-zjp51", "collection": "authors", "collection_id": "k0gn4-zjp51", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180807-125405326", "type": "article", "title": "Nanophotonic optical gyroscope with reciprocal sensitivity enhancement", "author": [ { "family_name": "Porsandeh Khial", "given_name": "Parham", "orcid": "0000-0002-3242-8541", "clpid": "Porsandeh-Khial-P" }, { "family_name": "White", "given_name": "Alexander D.", "orcid": "0000-0002-5387-310X", "clpid": "White-A-D" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Optical gyroscopes measure the rate of rotation by exploiting a relativistic phenomenon known as the Sagnac effect. Such gyroscopes are great candidates for miniaturization onto nanophotonic platforms. However, the signal-to-noise ratio of optical gyroscopes is generally limited by thermal fluctuations, component drift and fabrication mismatch. Due to the comparatively weaker signal strength at the microscale, integrated nanophotonic optical gyroscopes have not been realized so far. Here, we demonstrate an all-integrated nanophotonic optical gyroscope by exploiting the reciprocity of passive optical networks to significantly reduce thermal fluctuations and mismatch. The proof-of-concept device is capable of detecting phase shifts 30 times smaller than state-of-the-art miniature fibre-optic gyroscopes, despite being 500 times smaller in size. Thus, our approach is capable of enhancing the performance of optical gyroscopes by one to two orders of magnitude.", "doi": "10.1038/s41566-018-0266-5", "issn": "1749-4885", "publisher": "Nature Publishing Group", "publication": "Nature Photonics", "publication_date": "2018-11", "series_number": "11", "volume": "12", "issue": "11", "pages": "671-675" }, { "id": "authors:yeccs-mnz21", "collection": "authors", "collection_id": "yeccs-mnz21", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20180927-080601652", "type": "article", "title": "A 1-D heterodyne lens-free optical phased array camera with reference phase shifting", "author": [ { "family_name": "Abiri", "given_name": "Behrooz", "orcid": "0000-0002-3317-2752", "clpid": "Abiri-B" }, { "family_name": "Fatemi", "given_name": "Reza", "orcid": "0000-0001-9081-2608", "clpid": "Fatemi-R" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "This paper presents the first integrated silicon photonics optical phased array (OPA) receiver with imaging capabilities. A 32-element 1D OPA with an overall aperture size of 96x50 \u03bcm^2 is used to generate an electrically steerable \"gazing beam\". The OPA receiver elements couple the incident light to on-chip waveguides which is processed as a phased array receiver. To minimize signal loss and enhance sensitivity, a heterodyne architecture with phase shifters in the local reference path is utilized. The OPA receiver can provide fully programmable angular selectivity with a grating-lobe-free field-of-view of 30\u00b0 and a gazing beamwidth of 0.74\u00b0.", "doi": "10.1109/JPHOT.2018.2871823", "issn": "1943-0655", "publisher": "IEEE", "publication": "IEEE Photonics Journal", "publication_date": "2018-10", "series_number": "5", "volume": "10", "issue": "5", "pages": "Art. No. 6601712" }, { "id": "authors:3jj5p-h3q02", "collection": "authors", "collection_id": "3jj5p-h3q02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170929-075014830", "type": "article", "title": "Self-equalizing photodiodes, a hybrid electro-optical approach to tackle bandwidth limitation in high-speed signaling", "author": [ { "family_name": "Abiri", "given_name": "Behrooz", "orcid": "0000-0002-3317-2752", "clpid": "Abiri-B" }, { "family_name": "Aflatouni", "given_name": "Firooz", "clpid": "Aflatouni-F" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "In this paper we provide the design details of self-equalizing photodetectors which enable higher data rate transmission by improving the overall bandwidth of the bandwidth limited transmission link, through a hybrid electro-optical solution. Two different self-equalizing photodiodes, one having fixed equalization and the other being programmable are presented as proof of concept.", "doi": "10.1364/OE.25.019137", "issn": "1094-4087", "publisher": "Optical Society of America", "publication": "Optics Express", "publication_date": "2017-08-07", "series_number": "16", "volume": "25", "issue": "16", "pages": "19137-19146" }, { "id": "authors:ckk63-z0e22", "collection": "authors", "collection_id": "ckk63-z0e22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170503-094736352", "type": "article", "title": "Analysis of a balanced analog multiplier for an arbitrary number of signed inputs", "author": [ { "family_name": "Hong", "given_name": "Brian", "orcid": "0000-0001-8099-0312", "clpid": "Hong-Brian" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "We present an extension of the double-balanced current-commutating analog multiplier (also known as the Gilbert cell) that enables the multiplication of an arbitrary number of signed differential input voltages. A general analysis of the circuit for an arbitrary device nonlinearity is provided, and simulations on a bulk CMOS process as well as measurement results of a discrete bipolar implementation are reported.", "doi": "10.1002/cta.2243", "issn": "0098-9886", "publisher": "Wiley", "publication": "International Journal of Circuit Theory and Applications", "publication_date": "2017-04", "series_number": "4", "volume": "45", "issue": "4", "pages": "483-501" }, { "id": "authors:hkff6-qbv73", "collection": "authors", "collection_id": "hkff6-qbv73", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160930-143636537", "type": "article", "title": "Binary particle swarm optimized 2 \u00d7 2 power splitters in a standard foundry silicon photonic platform", "author": [ { "family_name": "Mak", "given_name": "Jason C. C.", "orcid": "0000-0003-2350-5813", "clpid": "Mak-J-C-C" }, { "family_name": "Sideris", "given_name": "Constantine", "orcid": "0000-0002-3042-4889", "clpid": "Sideris-C" }, { "family_name": "Jeong", "given_name": "Junho", "clpid": "Jeong-Junho" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Poon", "given_name": "Joyce K. S.", "clpid": "Poon-J-K-S" } ], "abstract": "Compact power splitters designed ab initio using binary particle swarm optimization in a 2D mesh for a standard foundry silicon photonic platform are studied. Designs with a 4.8\u2009\u2009\u03bcm\u00d74.8\u2009\u2009\u03bcm footprint composed of 200\u2009\u2009nm\u00d7200\u2009\u2009nm and 100\u2009\u2009nm\u00d7100\u2009\u2009nm cells are demonstrated. Despite not respecting design rules, the design with the smaller cells had lower insertion losses and broader bandwidth and showed consistent behavior across the wafer. Deviations between design and experiments point to the need for further investigations of the minimum feature dimensions.", "doi": "10.1364/OL.41.003868", "issn": "0146-9592", "publisher": "Optical Society of America", "publication": "Optics Letters", "publication_date": "2016-08-15", "series_number": "16", "volume": "41", "issue": "16", "pages": "3868-3871" }, { "id": "authors:g1knm-dmc94", "collection": "authors", "collection_id": "g1knm-dmc94", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20161014-084018774", "type": "article", "title": "Upper and lower bounds on a system's bandwidth based on its zero-value time constants", "author": [ { "family_name": "Hong", "given_name": "B.", "clpid": "Hong-Brian-D" }, { "family_name": "Hajimiri", "given_name": "A.", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "It is shown that for systems with no zeros and no complex poles, the classical estimate of the 3 dB cutoff frequency based on the sum of the zero-value time constants (ZVTs) is always conservative. The opposite problem is also solved, whereby a non-trivial upper bound on the cutoff frequency which depends only on the sum of the ZVTs and the system's order is derived. It is demonstrated that both bounds\nare tight \u2013 specifically, the lower bound is approached by making one of the system's poles increasingly dominant, whereas the best possible bandwidth is achieved when all of the system's poles overlap. The impact of complex poles on the results is also discussed.", "doi": "10.1049/e1.2016.1724", "issn": "0013-5194", "publisher": "Institution of Engineering and Technology (IET)", "publication": "Electronics Letters", "publication_date": "2016-08-04", "series_number": "16", "volume": "52", "issue": "16", "pages": "1383-1384" }, { "id": "authors:efptg-h6832", "collection": "authors", "collection_id": "efptg-h6832", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160802-080138135", "type": "article", "title": "Upper and lower bounds on a system's bandwidth based on its zero-value time constants", "author": [ { "family_name": "Hong", "given_name": "B.", "clpid": "Hong-B" }, { "family_name": "Hajimiri", "given_name": "A.", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "It is shown that for systems with no zeros and no complex poles, the classical estimate of the 3 dB cutoff frequency based on the sum of the zero-value time constants (ZVTs) is always conservative. A non-trivial upper bound on the cutoff frequency which depends only on the sum of the ZVTs and the system's order is also derived. It is demonstrated that both bounds are tight \u2013 specifically, the lower bound is approached by making one of the system's poles increasingly dominant, whereas the best possible bandwidth is achieved when all of the system's poles overlap. The impact of complex poles on the results is also discussed.", "doi": "10.1049/el.2016.1724", "issn": "0013-5194", "publisher": "Institution of Engineering and Technology", "publication": "Electronics Letters", "publication_date": "2016-08-04", "series_number": "16", "volume": "52", "issue": "16", "pages": "1383-1385" }, { "id": "authors:4f2xp-t3e22", "collection": "authors", "collection_id": "4f2xp-t3e22", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160825-104818056", "type": "article", "title": "Designing Optimal Surface Currents for Efficient On-Chip mm-Wave Radiators With Active Circuitry", "author": [ { "family_name": "Sengupta", "given_name": "Kaushik", "clpid": "Sengupta-K" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Integrated antennas have become the attractive solution as the electromagnetic (EM) interface for mm-Wave and terahertz ICs. However, on-chip antennas lying at the interface between two different dielectrics (such as air and substrate) can channel most of its power into multiple nonradiative surface-wave modes, reducing efficiency drastically. In this paper, we consider the following problem: given a dielectric substrate, what is the theoretical optimal 2-D surface-current configuration that collectively suppresses surface waves and maximizes radiation efficiency with the desirable radiation pattern? This paper also discusses demonstrative examples of a circuit-EM codesign approach to realize the approximation of such current configurations. Measurement results of radiating arrays in CMOS at mm-Wave frequencies (250-300 GHz) are presented and compared with theoretical predictions.", "doi": "10.1109/TMTT.2016.2573278", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2016-07", "series_number": "7", "volume": "64", "issue": "7", "pages": "1976-1988" }, { "id": "authors:a457j-1rf46", "collection": "authors", "collection_id": "a457j-1rf46", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160512-123859956", "type": "article", "title": "Dynamic Polarization Control of Two-Dimensional Integrated Phased Arrays", "author": [ { "family_name": "Safaripour", "given_name": "Amirreza", "orcid": "0000-0001-9758-6156", "clpid": "Safaripour-A" }, { "family_name": "Bowers", "given_name": "Steven M.", "clpid": "Bowers-S-M" }, { "family_name": "Dasgupta", "given_name": "Kaushik", "clpid": "Dasgupta-K" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Simultaneous two-dimensional (2-D) beam steering and dynamic polarization control (DPC) of the radiated electric field in 2-D phased arrays ensure polarization matching between the transmitter and receiver antennas in both fixed and mobile wireless systems. Polarization matching is maintained regardless of the polarization, orientation, and location of the receiver antenna in space within the 2-D steering range of the transmitter. This work implements a fully integrated 2 \u00d7 2 DPC phased-array transmitter in a 32-nm CMOS silicon-on-insulator process, radiating at 122.9 GHz. It achieves a maximum effective isotropic radiated power of +12.3 dBm in the broadside direction and enables polarization angle control of the radiated linear and elliptical polarizations across the full range of 0 \u00b0 to 180 \u00b0 with tunable axial ratio down to 1.2 dB to achieve circular polarization and the ability to steer the radiated beam up to 15 \u00b0 in both dimensions.", "doi": "10.1109/TMTT.2016.2530704", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2016-04", "series_number": "4", "volume": "64", "issue": "4", "pages": "1066-1077" }, { "id": "authors:v8v73-xwv09", "collection": "authors", "collection_id": "v8v73-xwv09", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160602-142331678", "type": "article", "title": "CMOS I/Q Subharmonic Mixer for Millimeter-Wave Atmospheric Remote Sensing", "author": [ { "family_name": "Parveg", "given_name": "Dristy", "clpid": "Parveg-D" }, { "family_name": "Varonen", "given_name": "Mikko", "clpid": "Varonen-M" }, { "family_name": "Kangaslahti", "given_name": "Pekka", "clpid": "Kangaslahti-P" }, { "family_name": "Safaripour", "given_name": "Amirreza", "orcid": "0000-0001-9758-6156", "clpid": "Safaripour-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Tikka", "given_name": "Tero", "clpid": "Tikka-T" }, { "family_name": "Gaier", "given_name": "Todd", "clpid": "Gaier-T" }, { "family_name": "Halonen", "given_name": "Kari A. I.", "clpid": "Halonen-K-A-I" } ], "abstract": "A compact second harmonic 180 GHz I/Q balanced resistive mixer is realized in a 32-nm SOI CMOS technology for atmospheric remote sensing applications. The MMIC further includes two on-chip IF amplifiers at the mixer's I and Q channels. A conversion gain of +8 dB is achieved with 74 mW of dc power consumption using a 1.2 V supply. The measured IF frequency range is from 1 to 10 GHz. The mixer achieves a 20 dB imagerejection (IR) ratio with an LO input power of +4 dBm. The chip size is 0.75 mm^2 including probing pads.", "doi": "10.1109/LMWC.2016.2537786", "issn": "1531-1309", "publisher": "IEEE", "publication": "IEEE Microwave and Wireless Components Letters", "publication_date": "2016-04", "series_number": "4", "volume": "26", "issue": "4", "pages": "285-287" }, { "id": "authors:yjv2a-kpz24", "collection": "authors", "collection_id": "yjv2a-kpz24", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20170111-150941985", "type": "article", "title": "200-GHz CMOS amplifier with 9-dB noise figure for atmospheric remote sensing", "author": [ { "family_name": "Varonen", "given_name": "M.", "clpid": "Varonen-M" }, { "family_name": "Safaripour", "given_name": "A.", "orcid": "0000-0001-9758-6156", "clpid": "Safaripour-A" }, { "family_name": "Parveg", "given_name": "D.", "clpid": "Parveg-D" }, { "family_name": "Kangaslahti", "given_name": "P.", "clpid": "Kangaslahti-P" }, { "family_name": "Gaier", "given_name": "T.", "clpid": "Gaier-T" }, { "family_name": "Hajimiri", "given_name": "A.", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "The feasibility of using CMOS technology for RF amplification in atmospheric remote sensing receiver is studied. The design and measurement results of a 200-GHz low-noise amplifier which is fabricated using a 32-nm SOI CMOS technology are presented. The 8-stage amplifier in a common-source configuration achieves a 9-dB noise figure and 25-dB gain with a power consumption of 33 mW.", "doi": "10.1049/el.2015.3337", "issn": "0013-5194", "publisher": "IET", "publication": "Electronics Letters", "publication_date": "2016-02-25", "series_number": "5", "volume": "52", "issue": "5", "pages": "369-371" }, { "id": "authors:1rszz-fb870", "collection": "authors", "collection_id": "1rszz-fb870", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151012-154703698", "type": "article", "title": "Mutual Synchronization for Power Generation and Beam-Steering in CMOS With On-Chip Sense Antennas Near 200 GHz", "author": [ { "family_name": "Sengupta", "given_name": "Kaushik", "clpid": "Sengupta-K" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "In this paper, we introduce the concept of near-field synchronization as an efficient, scalable, and robust method to synchronize a 2-D array of mutually coupled oscillators for beam-forming at frequencies above f_(max) of a technology. The method employs an array of on-chip sense antennas to probe electromagnetic near-fields of the on-chip radiators. These sense antennas are then coupled to each other appropriately through a network that establishes the synchronized state as the lowest energy state. A circuit-electromagnetic co-design methodology is employed to demonstrate beam-steering near 200 GHz with a synchronized 2 \u00d7 2 array. Each element of the array is a traveling-wave oscillator with the nonlinear active devices selectively radiating its second harmonic through the same electromagnetic structure. The beam-pattern can be varied by more than 70\u00b0 in both azimuth and elevation. The chip is realized in 65-nm bulk CMOS.", "doi": "10.1109/TMTT.2015.2457902", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2015-09", "series_number": "9", "volume": "63", "issue": "9", "pages": "2867-2876" }, { "id": "authors:jk49n-ay157", "collection": "authors", "collection_id": "jk49n-ay157", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151001-111516703", "type": "article", "title": "Nanophotonic projection system", "author": [ { "family_name": "Aflatouni", "given_name": "Firooz", "clpid": "Aflatouni-F" }, { "family_name": "Abiri", "given_name": "Behrooz", "orcid": "0000-0002-3317-2752", "clpid": "Abiri-B" }, { "family_name": "Rekhi", "given_name": "Angad", "clpid": "Rekhi-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Low-power integrated projection technology can play a key role in development of low-cost mobile devices with built-in high-resolution projectors. Low-cost 3D imaging and holography systems are also among applications of such a technology. In this paper, an integrated projection system based on a two-dimensional optical phased array with fast beam steering capability is reported. Forward biased p-i-n phase modulators with 200MHz bandwidth are used per each array element for rapid phase control. An optimization algorithm is implemented to compensate for the phase dependent attenuation of the p-i-n modulators. Using rapid vector scanning technique, images were formed and recorded within a single snapshot of the IR camera.", "doi": "10.1364/OE.23.021012", "issn": "1094-4087", "publisher": "Optical Society of America", "publication": "Optics Express", "publication_date": "2015-08-10", "series_number": "16", "volume": "23", "issue": "16", "pages": "21012-21022" }, { "id": "authors:x7r7g-2xw89", "collection": "authors", "collection_id": "x7r7g-2xw89", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150602-162920874", "type": "article", "title": "Functionalized iron oxide nanoparticles for controlling the movement of immune cells", "author": [ { "family_name": "White", "given_name": "Ethan E.", "clpid": "White-Ethan-E" }, { "family_name": "Pai", "given_name": "Alex", "clpid": "Pai-Alex" }, { "family_name": "Weng", "given_name": "Yiming", "clpid": "Weng-Yiming" }, { "family_name": "Suresh", "given_name": "Anil K.", "clpid": "Suresh-Anil-K" }, { "family_name": "Van Haute", "given_name": "Desiree", "clpid": "Van-Haute-Dseriee" }, { "family_name": "Pailevanian", "given_name": "Torkom", "clpid": "Pailevanian-Torkom" }, { "family_name": "Alizadeh", "given_name": "Darya", "orcid": "0000-0002-8470-5424", "clpid": "Alizadeh-Darya" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Badie", "given_name": "Behnam", "orcid": "0000-0001-9811-9306", "clpid": "Badie-Behnam" }, { "family_name": "Berlin", "given_name": "Jacob M.", "orcid": "0000-0001-7498-766X", "clpid": "Berlin-Jacob-M" } ], "abstract": "Immunotherapy is currently being investigated for the treatment of many diseases, including cancer. The ability to control the location of immune cells during or following activation would represent a powerful new technique for this field. Targeted magnetic delivery is emerging as a technique for controlling cell movement and localization. Here we show that this technique can be extended to microglia, the primary phagocytic immune cells in the central nervous system. The magnetized microglia were generated by loading the cells with iron oxide nanoparticles functionalized with CpG oligonucleotides, serving as a proof of principle that nanoparticles can be used to both deliver an immunostimulatory cargo to cells and to control the movement of the cells. The nanoparticle-oligonucleotide conjugates are efficiently internalized, non-toxic, and immunostimulatory. We demonstrate that the in vitro migration of the adherent, loaded microglia can be controlled by an external magnetic field and that magnetically-induced migration is non-cytotoxic. In order to capture video of this magnetically-induced migration of loaded cells, a novel 3D-printed \"cell box\" was designed to facilitate our imaging application. Analysis of cell movement velocities clearly demonstrate increased cell velocities toward the magnet. These studies represent the initial step towards our final goal of using nanoparticles to both activate immune cells and to control their trafficking within the diseased brain.", "doi": "10.1039/c3nr04421a", "pmcid": "PMC4409571", "issn": "2040-3372", "publisher": "Royal Society of Chemistry", "publication": "Nanoscale", "publication_date": "2015-05-07", "series_number": "17", "volume": "7", "issue": "17", "pages": "7780-7789" }, { "id": "authors:k5ngx-5s849", "collection": "authors", "collection_id": "k5ngx-5s849", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150508-105530561", "type": "article", "title": "Dynamic Polarization Control", "author": [ { "family_name": "Bowers", "given_name": "Steven M.", "clpid": "Bowers-S-M" }, { "family_name": "Safaripour", "given_name": "Amirreza", "orcid": "0000-0001-9758-6156", "clpid": "Safaripour-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Dynamic polarization control (DPC) is the method of setting the polarization of the far-field electric field generated by a radiating antenna entirely electronically in order to maintain polarization matching with the receiving antenna regardless of its polarization or orientation in space. This work implements a fully integrated 2 \u00d7 1 phased array radiator in 32 nm CMOS SOI at 105.5 GHz with DPC. The system consists of a central locking oscillator that phase locks oscillators within the core of each antenna followed by three amplification stages with variable gain that drive the antennas. By controlling the amplitude and phase of two orthogonal polarized subparts of each multi-port antenna, various far-field polarizations can be realized. The array is capable of beam steering, controlling the polarization angle across the entire tuning range of 0\u00b0 to 180\u00b0 while maintaining axial ratios above 10 dB, and controlling the axial ratio from 2.4 dB (near circular) to 14 dB (linear) in various directions of radiation. It radiates a maximum EIRP of 7.8 dBm with a total radiated power of 0.9 mW. To the best of the authors' knowledge, this work presents the first integrated radiator with dynamically controllable polarization.", "doi": "10.1109/JSSC.2015.2403313", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2015-05", "series_number": "5", "volume": "50", "issue": "5", "pages": "1224-1236" }, { "id": "authors:hw8r9-wz759", "collection": "authors", "collection_id": "hw8r9-wz759", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150602-153730543", "type": "article", "title": "Silicon Integrated 280 GHz Imaging Chipset With 4x4 SiGe Receiver Array and CMOS Source", "author": [ { "family_name": "Sengupta", "given_name": "Kaushik", "clpid": "Sengupta-K" }, { "family_name": "Seo", "given_name": "Dongjin", "clpid": "Seo-Dongjin" }, { "family_name": "Yang", "given_name": "Lita", "clpid": "Yang-Lita" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "In this paper, we report an integrated silicon-based active imaging chipset with a detector array in 0.13 \u03bcm SiGe process and a CMOS-based source array operating in the 240-290 GHz range. The chipset operates at room-temperature with no external RF or optical sources, high-resistivity silicon lenses (HRSi) or waveguides or any custom fabrication options, such as high-resistivity substrates or substrate thinning. The receiver chip consists of a 2-D array of 16 pixels, measuring 2.5 mm \u00d7 2.5 mm with integrated antennas. An electromagnetic-active circuit co-design approach is carried out to ensure high-efficiency interface with detectors operating above cut-off frequencies with good impedance matching, near-optimal noise performance, while simultaneously suppressing the dominant surface-wave modes in a lensless lossy bulk silicon substrate. The array performance is characterized in the WR-3 band between 220-320 GHz. At the designed frequency of 260 GHz, the NEP of all pixels stays between 7.9 pW/\u221a{Hz}-8.8 pW/\u221a{Hz}. The imaging chipset consists of this 2D detector array chip and a CMOS-based source array chip measuring 0.8 mm \u00d7 0.8 mm. The entire system dissipates less than 180 mW of DC power, representing a truly integrated solution.", "doi": "10.1109/TTHZ.2015.2414826", "issn": "2156-342X", "publisher": "IEEE", "publication": "IEEE Transactions on Terahertz Science and Technology", "publication_date": "2015-05", "series_number": "3", "volume": "5", "issue": "3", "pages": "427-437" }, { "id": "authors:7z409-crs43", "collection": "authors", "collection_id": "7z409-crs43", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150508-085919032", "type": "article", "title": "An Integrated Slot-Ring Traveling-Wave Radiator", "author": [ { "family_name": "Bowers", "given_name": "Steven M.", "clpid": "Bowers-S-M" }, { "family_name": "Safaripour", "given_name": "Amirreza", "orcid": "0000-0001-9758-6156", "clpid": "Safaripour-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Electromagnetic duality is used to design a multi-port traveling-wave slot-ring antenna with on-chip driver circuitry to create a fully integrated radiator. By creating a slot version of the multi-port driven antenna, the required exclusive use area of the antenna is significantly decreased, while still being able to perform impedance matching, power combining, and power transfer off chip through electromagnetic radiation in a single step. The driver core consists of an oscillator followed by three amplification stages. A split path inductor design was utilized to reduce the radiator's dependence on process variation in the metal stack while ensuring proper isolation between the four quadrature paths. The slot radiator has a simulated antenna efficiency of 39% and a measured single-element effective isotropic radiated power of 6.0 dBm with a total radiated power of -1.3 dBm at 134.5 GHz.", "doi": "10.1109/TMTT.2015.2405921", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2015-04", "series_number": "4", "volume": "63", "issue": "4", "pages": "1154-1162" }, { "id": "authors:j3fek-8xv08", "collection": "authors", "collection_id": "j3fek-8xv08", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150507-141744018", "type": "article", "title": "A mm-Wave Segmented Power Mixer", "author": [ { "family_name": "Dasgupta", "given_name": "Kaushik", "clpid": "Dasgupta-K" }, { "family_name": "Sengupta", "given_name": "Kaushik", "clpid": "Sengupta-K" }, { "family_name": "Pai", "given_name": "Alex", "clpid": "Pai-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "The segmented power-mixer array based mm-wave power generation architecture is demonstrated to be an energy-efficient technique for generating high-speed nonconstant envelope modulations. High output power levels are achieved by efficiently combining power from several power mixers using an area efficient dual-primary distributed active transformer. The segmented scheme leads to back-off efficiency improvements while simultaneously providing direct envelope modulation eliminating the need for high-speed high-efficiency supply modulators. The power mixer is implemented in a 32-nm silicon-on-insulator CMOS process and provides a peak output power of 19.1 dBm at 51 GHz with a drain efficiency of 14.2% and a peak power-added efficiency of 10.1%. High-speed constant (binary phase-shift keying, quadrature phase-shift keying), as well as nonconstant envelope modulations ( m-amplitude shift keying, quadrature amplitude modulation) show the versatility of the architecture towards spectrally efficient modulation schemes. Reliability against segment breakdown over long periods of time at 30% higher supply voltages has also been demonstrated.", "doi": "10.1109/TMTT.2015.2409094", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2015-04", "series_number": "4", "volume": "63", "issue": "4", "pages": "1118-1129" }, { "id": "authors:z7wdg-gpw27", "collection": "authors", "collection_id": "z7wdg-gpw27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150403-092301542", "type": "article", "title": "Nanophotonic coherent imager", "author": [ { "family_name": "Aflatouni", "given_name": "Firooz", "clpid": "Aflatouni-F" }, { "family_name": "Abiri", "given_name": "Behrooz", "orcid": "0000-0002-3317-2752", "clpid": "Abiri-B" }, { "family_name": "Rekhi", "given_name": "Angad", "clpid": "Rekhi-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "An integrated silicon nanophotonic coherent imager (NCI), with a 4 \u00d7 4 array of coherent pixels is reported. In the proposed NCI, on-chip optical processing determines the intensity and depth of each point on the imaged object based on the instantaneous phase and amplitude of the optical wave incident on each pixel. The NCI operates based on a modified time-domain frequency modulated continuous wave (FMCW) ranging scheme, where concurrent time-domain measurements of both period and the zero-crossing time of each electrical output of the nanophotonic chip allows the NCI to overcome the traditional resolution limits of frequency domain detection. The detection of both intensity and relative delay enables applications such as high-resolution 3D reflective and transmissive imaging as well as index contrast imaging. We demonstrate 3D imaging with 15\u03bcm depth resolution and 50\u03bcm lateral resolution (limited by the pixel spacing) at up to 0.5-meter range. The reported NCI is also capable of detecting a 1% equivalent refractive index contrast at 1mm thickness.", "doi": "10.1364/OE.23.005117", "issn": "1094-4087", "publisher": "Optical Society of America", "publication": "Optics Express", "publication_date": "2015-02-19", "series_number": "4", "volume": "23", "issue": "4", "pages": "5117-5125" }, { "id": "authors:zsgwa-rjv65", "collection": "authors", "collection_id": "zsgwa-rjv65", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150106-084828698", "type": "article", "title": "A self-correcting quadrature voltage controlled oscillator", "author": [ { "family_name": "Arai", "given_name": "Tomoyuki", "clpid": "Arai-Tomoyuki" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A self-correcting quadrature voltage controlled oscillator (QVCO) with phase correcting loop is proposed. It comprises the QVCO core and phase correcting loop, which corrects the quadrature phase error. Two LC VCOs, buffers, and phase shifters are coupled in circular configuration to achieve IQ symmetry. This paper introduces the idea of realizing QVCO with low phase noise and accurate quadrature phase by using the phase correcting loop. The simulation results based on the 65 nm CMOS process show that the self-correcting QVCO has a phase error less than 0.5\u00b0 and 1 MHz offset phase noise of \u2212120 dBc/Hz at 3.7 GHz with 49% tuning range.", "doi": "10.1587/elex.11.20140684", "issn": "1349-2543", "publisher": "Institute of Electronics, Information and Communication Engineers", "publication": "IEICE Electronics Express", "publication_date": "2014-10-11", "series_number": "19", "volume": "11", "issue": "19", "pages": "Art. No." }, { "id": "authors:h5kbe-h1m60", "collection": "authors", "collection_id": "h5kbe-h1m60", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140130-085232364", "type": "article", "title": "A handheld magnetic sensing platform for antigen and nucleic acid detection", "author": [ { "family_name": "Pai", "given_name": "Alex", "clpid": "Pai-Alex" }, { "family_name": "Khachaturian", "given_name": "Aroutin", "orcid": "0000-0001-8304-3302", "clpid": "Khachaturian-A" }, { "family_name": "Chapman", "given_name": "Stephen", "clpid": "Chapman-S-A" }, { "family_name": "Hu", "given_name": "Alexander", "clpid": "Hu-Alexander" }, { "family_name": "Wang", "given_name": "Hua", "clpid": "Wang-Hua" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "The core requirements for point-of-care (POC) diagnostics necessitate low-cost, portability, easily integrated sample preparation, and quick measurement time. Frequency-shift based magnetic sensing is a measurement technique utilizing a complementary metal-oxide-semiconductor (CMOS) integrated-circuit (IC) chip for magnetic label detection. The sensing scheme leverages the low-cost manufacturing of IC chips while demonstrating the potential for multiplexing capabilities. In this article, we present modifications to this scheme for POC viability. We introduce a handheld reusable reader and a disposable open-well cartridge for the detection of nucleic acids and antigens. The diagnostic system utilizes a novel \"magnetic freezing\" technique to reduce measurement time, obviates baseline measurement before or during biological assay, and reduces sensor noise. We utilize these enhancements for the room temperature, amplification-free detection of a 31 base-pair DNA oligomer and the interferon-\u03b3 (IFN-\u03b3) protein. We have demonstrated reliable measurements down to 100 pM for the DNA assay and 1 pM for the protein.", "doi": "10.1039/C3AN01947K", "issn": "0003-2654", "publisher": "Royal Society of Chemistry", "publication": "Analyst", "publication_date": "2013-12-10", "series_number": "6", "volume": "139", "issue": "6", "pages": "1403-1411" }, { "id": "authors:kv000-0zt42", "collection": "authors", "collection_id": "kv000-0zt42", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140221-094415202", "type": "article", "title": "Design and Implementation of an Integrated Magnetic Spectrometer for Multiplexed Biosensing", "author": [ { "family_name": "Sideris", "given_name": "Constantine", "orcid": "0000-0002-3042-4889", "clpid": "Sideris-C" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Magnetic spectroscopy allows for characterization of the magnetic susceptibility of magnetic beads across a broad frequency range. This enables differentiation and quantification of multiple beads of varying types concurrently present in the active volume of a sensor's surface. A magnetic spectrometer can be used for multi-probe tagging and identification akin to multi-color fluorescent bio-sensing. We propose a new sensing methodology to perform magnetic spectroscopy and analyze various important design parameters such as SNR and gain uniformity. We present a proof-of-concept design of a fully integrated CMOS magnetic spectrometer that can detect, quantify, and characterize magnetic materials in the 1.1 GHz to 3.3 GHz frequency range, where we demonstrate magnetic multiplexing capability using a mixture of two different kinds of magnetic beads. The sensor consumes less than 2 mW of DC power within the whole frequency range, requires no external biasing magnetic fields, is implemented in a standard CMOS process, and can be powered and operated completely from a USB interface. The magnetic spectrometer not only increases the throughput and multiplexing of biosensing experiments for a given sensor area, but also can enable additional applications, such as magnetic flow cytometry and signal-collocation assays of multiple probes.", "doi": "10.1109/TBCAS.2013.2297514", "issn": "1932-4545", "publisher": "IEEE", "publication": "IEEE Transactions on Biomedical Circuits and Systems", "publication_date": "2013-12", "series_number": "6", "volume": "7", "issue": "6", "pages": "773-784" }, { "id": "authors:rfrtc-sck96", "collection": "authors", "collection_id": "rfrtc-sck96", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140103-085626421", "type": "article", "title": "Multi-Port Driven Radiators", "author": [ { "family_name": "Bowers", "given_name": "Steven M.", "clpid": "Bowers-S-M" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Integrated multi-port driven (MPD) radiator design is presented as an approach that takes advantage of the increased design space offered by using a hybrid design of an antenna with multiple ports and its driver circuitry integrated together on a single substrate. This reduces costly losses by eliminating independent elements for power combination, output impedance matching networks, and power transfer by engineering current patterns on a chip based on the desired far field pattern. The electromagnetic radiation produced by a circularly polarized MPD antenna is calculated analytically to provide design intuition, with supporting electromagnetic simulations. A single element 160 GHz MPD antenna and the supporting driver circuitry is designed and fabricated in a 0.13 \u03bcm SiGe BiCMOS process. A tuned 8 phase ring oscillator generates the signal with each phase feeding class A power amplifiers that drive the antenna. The radiator achieves 4.6 dBm single element effective isotropically radiated power (EIRP) and total radiated power of -2.0 dBm at 161 GHz while consuming 117.5 mA DC current from a 3.3 V source. Measurements of three frequency bands at 145, 154 and 161 GHz show greater than 0 dBm EIRP for each band, demonstrating the wide band nature of the antenna.", "doi": "10.1109/TMTT.2013.2288230", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2013-12", "series_number": "12", "volume": "61", "issue": "12", "pages": "4428-4441" }, { "id": "authors:jnf07-0d064", "collection": "authors", "collection_id": "jnf07-0d064", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130621-130626802", "type": "article", "title": "Phase Noise and Fundamental Sensitivity of Oscillator-Based Reactance Sensors", "author": [ { "family_name": "Wang", "given_name": "Hua", "clpid": "Wang-Hua" }, { "family_name": "Weng", "given_name": "Ching-Chih", "clpid": "Weng-Ching-Chih" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "This paper investigates the fundamental sensitivity of oscillator-based reactance sensors, which are widely used in numerous types of biomedical sensing applications. We first show that the intrinsic sensitivity is limited by the 1/\u0192^3 phase noise of the sensing oscillators. To achieve sensor detection sensitivity below this limit, a correlated double counting (CDC) noise suppression scheme is proposed to cancel the correlated 1/\u0192^3 phase noise in differential frequency detections. The suppression effect of the CDC scheme is thoroughly modeled. Moreover, the CDC scheme is extended to a high-order configuration, called the Interleaving-N CDC, to further improve the frequency resolution. In addition, we show that the weighting sequence on the Interleaving-N CDC data can be optimized as a digital noise filter to maximize the noise suppression. Given a sensing oscillator with any phase-noise profile, a general weighting optimization method is proposed based on the minimum variance distortion less response. As an example, an oscillator-based inductive magnetic sensor array in a 45-nm CMOS silicon-on-insulator process is implemented with the proposed CDC scheme. It achieves a noise suppression of 10.4 dB with basic CDC sheme and a frequency resolution of 0.128 parts per million for Interleaving-N CDC scheme, both with negligible power overhead. This enables inductance-change detection sensitivity of 0.41 fH for a low-Q on-chip 1.6-nH inductor with a quality factor of only 4.95.", "doi": "10.1109/TMTT.2013.2256142", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2013-05", "series_number": "5", "volume": "61", "issue": "5", "pages": "2215-2229" }, { "id": "authors:evmya-cxy76", "collection": "authors", "collection_id": "evmya-cxy76", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130424-154627947", "type": "article", "title": "Integrated Self-Healing for mm-Wave Power Amplifiers", "author": [ { "family_name": "Bowers", "given_name": "Steven M.", "clpid": "Bowers-S-M" }, { "family_name": "Sengupta", "given_name": "Kaushik", "clpid": "Sengupta-K" }, { "family_name": "Dasgupta", "given_name": "Kaushik", "clpid": "Dasgupta-K" }, { "family_name": "Parker", "given_name": "Benjamin D.", "clpid": "Parker-B-D" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Self-healing as a technique for improving performance and yield of millimeter-wave power amplifiers (PAs) against process variation and transistor mismatch, load impedance mismatch, and partial and total transistor failure is described and investigated. A 28-GHz PA is presented with three types of sensors, two types of actuators, data converters, and a digital algorithm block that are all integrated on a single chip to show the validity of the technique. Two algorithms are implemented to either maximize output power or to minimize dc power for a desired output power. Measurements from 20 chips show increased RF output power up to 3 dB or reduced dc power by 50% in backoff with a 50-\u03a9 load. Self-healing with up to 4-1 voltage standing-wave ratio load impedance mismatch is verified and linear operation under nonconstant envelope modulation is shown to improve with healing. Self-healing after laser cutter induced transistor failure is verified and increases RF output power by up to 5.4 dB. The aggregate yield of the PA across several representative specifications is increased from 0% to 80% with self-healing.", "doi": "10.1109/TMTT.2013.2243750", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2013-03", "series_number": "3", "volume": "61", "issue": "3", "pages": "1301-1315" }, { "id": "authors:3wvx1-2qx29", "collection": "authors", "collection_id": "3wvx1-2qx29", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20130220-142334283", "type": "article", "title": "A 0.28 THz Power-Generation and Beam-Steering Array in CMOS Based on Distributed Active Radiators", "author": [ { "family_name": "Sengupta", "given_name": "Kaushik", "clpid": "Sengupta-K" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "In this paper, we present a scalable transmitter architecture for power generation and beam-steering at THz frequencies using a centralized frequency reference, sub-harmonic signal distribution, and local phase control. The power generation and radiator core is based on a novel method called distributed active radiation, which enables high conversion efficiency from DC to radiated terahertz power above f_(max) of a technology. The design evolution of the distributed active radiator (DAR) follows from an inverse design approach, where metal surface currents at different harmonics are formulated in the silicon chip for the desired electromagnetic field profiles. Circuits and passives are then designed conjointly to synthesize and control the surface currents. The DAR consists of a self-oscillating active electromagnetic structure, comprising of two loops which sustain out-of-phase currents at the fundamental frequency and in-phase currents at the second harmonic. The fundamental signal, thus gets, spatially filtered, while the second harmonic is radiated selectively, thereby consolidating signal generation, frequency multiplication, radiation of desired harmonic and filtration of undesired harmonics simultaneously in a small silicon footprint. A two-dimensional 4\u00d74 radiating array implemented in 45 nm SOI CMOS (without high-resistivity substrate) radiates with an EIRP of +9.4 dBm at 0.28 THz and beam-steers in 2D over 80\u00b0 in both azimuth and elevation. The chip occupies 2.7 mm \u00d7 2.7 mm and dissipates 820 mW of DC power. To the best of the authors' knowledge, this is the first reported integrated beam-scanning array at THz frequencies in silicon.", "doi": "10.1109/JSSC.2012.2217831", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2012-12", "series_number": "12", "volume": "47", "issue": "12", "pages": "3013-3031" }, { "id": "authors:1vqc6-8rn55", "collection": "authors", "collection_id": "1vqc6-8rn55", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120919-115826812", "type": "article", "title": "A magnetic cell-based sensor", "author": [ { "family_name": "Wang", "given_name": "Hua", "clpid": "Wang-Hua" }, { "family_name": "Mahdavi", "given_name": "Alborz", "orcid": "0000-0002-8790-8112", "clpid": "Mahdavi-Alborz" }, { "family_name": "Tirrell", "given_name": "David A.", "orcid": "0000-0003-3175-4596", "clpid": "Tirrell-D-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Cell-based sensing represents a new paradigm for performing direct and accurate detection of cell- or tissue-specific responses by incorporating living cells or tissues as an integral part of a sensor. Here we report a new magnetic cell-based sensing platform by combining magnetic sensors implemented in the complementary metal-oxide-semiconductor (CMOS) integrated microelectronics process with cardiac progenitor cells that are differentiated directly on-chip. We show that the pulsatile movements of on-chip cardiac progenitor cells can be monitored in a real-time manner. Our work provides a new low-cost approach to enable high-throughput screening systems as used in drug development and hand-held devices for point-of-care (PoC) biomedical diagnostic applications.", "doi": "10.1039/C2LC40392G", "issn": "1473-0197", "publisher": "Royal Society of Chemistry", "publication": "Lab on a Chip", "publication_date": "2012-08-14", "series_number": "21", "volume": "12", "issue": "21", "pages": "4465-4471" }, { "id": "authors:h76cn-k2p09", "collection": "authors", "collection_id": "h76cn-k2p09", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120608-092557453", "type": "article", "title": "A Wide-Swing Low-Noise Transconductance Amplifier and the Enabling of Large-Signal Handling Direct-Conversion Receivers", "author": [ { "family_name": "Keehr", "given_name": "Edward A.", "clpid": "Keehr-E-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "In this paper, the design of a wide-swing low-noise transconductance amplifier (LNTA) is presented in the context of passive mixer-based direct-conversion RF receivers, noting that the compression performance of such systems is limited by the initial voltage-to-current conversion. The proposed LNTA utilizes a stacked PMOS/NMOS common-gate configuration with its input common-mode voltage maintained by a class-AB operational transconductance amplifier (OTA). Linearization mechanisms and design procedures are explained both quantitatively and intuitively. Simulations of the LNTA at the typical corner, when ideally loaded, show an IIP3 + 32.8 dBm extrapolated at +12.5 dBm/-16.5 dBm CW blocking condition and an out-of-band 1-dB desensitization point of +22 dBm. These results are also shown to qualitatively agree with those extracted from an analytical model of the LNTA.", "doi": "10.1109/TCSI.2011.2161367", "issn": "1549-8328", "publisher": "IEEE", "publication": "IEEE Transactions on Circuits and Systems", "publication_date": "2012-01", "series_number": "1", "volume": "59", "issue": "1", "pages": "30-43" }, { "id": "authors:aw9ha-tbk88", "collection": "authors", "collection_id": "aw9ha-tbk88", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20120104-113526830", "type": "article", "title": "A 12.5+12.5 Gb/s Full-Duplex Plastic Waveguide Interconnect", "author": [ { "family_name": "Fukuda", "given_name": "Satoshi", "clpid": "Fukuda-S" }, { "family_name": "Hino", "given_name": "Yasufumi", "clpid": "Hino-Y" }, { "family_name": "Ohashi", "given_name": "Sho", "clpid": "Ohashi-S" }, { "family_name": "Takeda", "given_name": "Takahiro", "clpid": "Takeda-T" }, { "family_name": "Yamagishi", "given_name": "Hiroyuki", "clpid": "Yamagishi-H" }, { "family_name": "Shinke", "given_name": "Satoru", "clpid": "Shinke-S" }, { "family_name": "Komori", "given_name": "Kenji", "clpid": "Komori-K" }, { "family_name": "Uno", "given_name": "Masahiro", "clpid": "Uno-M" }, { "family_name": "Akiyama", "given_name": "Yoshiyuki", "clpid": "Akiyama-Y" }, { "family_name": "Kawasaki", "given_name": "Kenichi", "clpid": "Kawasaki-K" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A new interconnect solution with plastic waveguide is demonstrated. The system consists of a pair of transceivers and a plastic waveguide. Millimeter wave signal is transmitted in a low-cost long piece of solid plastic dielectric acting as a waveguide. The plastic waveguide medium offers a large bandwidth for data communication using mm-wave carrier frequencies. Plastic waveguide interconnects do not require costly electrical-to-optical and optical-to-electrical conversion devices or precise alignment and offer longer transmission distances than wireless solutions due to better field confinement and lower path loss. Multiple plastic waveguides can be used in parallel and the modulated data at different frequencies can be multiplexed to increase the data rate. The demonstrated transceiver chips operate at carrier frequencies of 57 GHz and 80 GHz, and are fabricated in 40 nm low-power logic CMOS. The total area and power consumption of two transceivers are 0.41 mm^2 and 140 mW, respectively. The fabricated demonstrator with Yagi-couplers achieves full-duplex transmission of 12.5 Gb/s ASK modulated signal in each direction over the 120 mm polystyrene waveguide with no equalization. The observed bit error rates for both channels are less than 10^(-12) for a PRBS length of 2^(7)-1 at the total data rate of 25 Gb/s. This paper shows the feasibility of the plastic waveguide interconnect as a promising alternative to electrical, optical, and wireless interconnects.", "doi": "10.1109/JSSC.2011.2168870", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2011-12", "series_number": "12", "volume": "46", "issue": "12", "pages": "3113-3125" }, { "id": "authors:bamv5-g9769", "collection": "authors", "collection_id": "bamv5-g9769", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110531-081045930", "type": "article", "title": "Successive Regeneration and Adaptive Cancellation of Higher Order Intermodulation Products in RF Receivers", "author": [ { "family_name": "Keehr", "given_name": "Edward A.", "clpid": "Keehr-E-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "In this paper, a general framework for the adaptive\nfeedforward cancellation of higher order intermodulation distortion\n(IMD) products is presented. By generating only second-order\nand principal-odd-order IMD reference products in the RF/analog\ndomain and reproducing higher order IMD reference products at\ndigital baseband, the proposed reference distortion scheme minimizes\nthe analog hardware burden on the system. Inherent in this\nprocedure is an approximation that the profile of blocking signals\ncausing IMD is dominated by one very large blocker. The limitations\nimposed by this approximation are quantitatively examined\nand shown to permit cancellation ratios of nearly the square\nof the ratio between the dominant and nondominant blocking\nsignal RMS amplitudes. An experimental receiver employing\nthe proposed technique was constructed utilizing a wide-swing\nlow-noise transconductance amplifier in order to accommodate a\nrail-to-rail (+12.4 dBm) out-of-band blocker and a -16.3-dBm\nnondominant blocker. The measured receiver out-of-band 1-dB\ndesensitization point is +12.5 dBm and the peak uncorrected\ntwo-tone third-order intermodulation intercept point (IIP3) is\n+33.5 dBm. Utilizing the proposed IMD cancellation scheme in\nthe presence of a modulated dominant blocker improves the total\ninput-referred IMD error power by over 24 dB, resulting in an\nextrapolated IIP3 metric of +43.5 dBm.", "doi": "10.1109/TMTT.2011.2123107", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2011-05", "series_number": "5", "volume": "59", "issue": "5", "pages": "1379-1396" }, { "id": "authors:z6bh9-6ma82", "collection": "authors", "collection_id": "z6bh9-6ma82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110310-133536770", "type": "article", "title": "Solving Large-Scale Hybrid Circuit-Antenna Problems", "author": [ { "family_name": "Lavaei", "given_name": "Javad", "clpid": "Lavaei-J" }, { "family_name": "Babakhani", "given_name": "Aydin", "clpid": "Babakhani-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Doyle", "given_name": "John C.", "orcid": "0000-0002-1828-2486", "clpid": "Doyle-J-C" } ], "abstract": "Motivated by different applications in circuits, electromagnetics, and optics, this paper is concerned with the synthesis of a particular type of linear circuit, where the circuit is associated with a control unit. The objective is to design a controller for this control unit such that certain specifications on the parameters of the circuit are satisfied. It is shown that designing a control unit in the form of a switching network is an NP-complete problem that can be formulated as a rank-minimization problem. It is then proven that the underlying design problem can be cast as a semidefinite optimization if a passive network is designed instead of a switching network. Since the implementation of a passive network may need too many components, the design of a decoupled (sparse) passive network is subsequently studied. This paper introduces a tradeoff between design simplicity and implementation complexity for an important class of linear circuits. The superiority of the developed techniques is demonstrated by different simulations. In particular, for the first time in the literature, a wavelength-size passive antenna is designed, which has an excellent beamforming capability and which can concurrently make a null in at least eight directions.", "doi": "10.1109/TCSI.2010.2072010", "issn": "1549-8328", "publisher": "IEEE", "publication": "IEEE Transactions on Circuits and Systems I: Regular Papers", "publication_date": "2011-02", "series_number": "2", "volume": "58", "issue": "2", "pages": "374-387" }, { "id": "authors:pynk1-h9c52", "collection": "authors", "collection_id": "pynk1-h9c52", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110324-091631996", "type": "article", "title": "Next-Generation CMOS RF Power Amplifiers", "author": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Ten years ago, it was widely accepted conventional wisdom that wattlevel fully integrated power amplifiers (PAs) were not feasible in standard complimentary metal-oxide-semiconductor (CMOS) technology. Today millions of such devices are commercially produced and shipped every month and are used in hundreds of millions of cellular phones across the world. Such dramatic transition from being considered an impossibility even by most optimistic academics to the obvious future direction to be followed by everyone happened through a series of demonstrations based on new architectures radically different from the known PA topologies applied over more than half a century.", "doi": "10.1109/MMM.2010.939321", "issn": "1527-3342", "publisher": "IEEE", "publication": "IEEE Microwave Magazine", "publication_date": "2011-02", "series_number": "1", "volume": "12", "issue": "1", "pages": "38-45" }, { "id": "authors:8c051-c0395", "collection": "authors", "collection_id": "8c051-c0395", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20110112-123555604", "type": "article", "title": "A CMOS Broadband Power Amplifier With a Transformer-Based High-Order Output Matching Network", "author": [ { "family_name": "Wang", "given_name": "Hua", "clpid": "Wang-Hua" }, { "family_name": "Sideris", "given_name": "Constantine", "orcid": "0000-0002-3042-4889", "clpid": "Sideris-C" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A transformer-based high-order output matching network is proposed for broadband power amplifier design, which\nprovides optimum load impedance for maximum output power\nwithin a wide operating frequency range. A design methodology to convert a canonical bandpass network to the proposed matching configuration is also presented in detail. As a design example, a push-pull deep class-AB PA is implemented with a third-order output network in a standard 90 nm CMOS process. The leakage inductances of the on-chip 2:1 transformer are absorbed into the output matching to realize the third-order network with only two\ninductor footprints for area conservation. The amplifier achieves a 3 dB bandwidth from 5.2 to 13 GHz with +25.2 dBm peak P_sat and 21.6% peak PAE. The EVM for QPSK and 16-QAM signals both with 5 Msample/s are below 3.6% and 5.9% at the output 1 dB compression point. This verifies the PA's capability of amplifying a narrowband modulated signal whose center-tone can be programmed across a large frequency range. The measured BER for transmitting a truly broadband PRBS signal up to 7.5 Gb/s is less than 10^(-13) , demonstrating the PA's support for an instantaneous wide operation bandwidth.", "doi": "10.1109/JSSC.2010.2077171", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2010-12", "series_number": "12", "volume": "45", "issue": "12", "pages": "2709-2722" }, { "id": "authors:hpgvj-krt05", "collection": "authors", "collection_id": "hpgvj-krt05", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20101011-132051958", "type": "article", "title": "Generalized Time- and Transfer-Constant Circuit Analysis", "author": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "The generalized method of time and transfer constants\nis introduced. It can be used to determine the transfer\nfunction to the desired level of accuracy in terms of time and\ntransfer constants of first-order systems using exclusively low\nfrequency calculations. This method can be used to determine the\npoles and zeros of circuits with both inductors and capacitors.\nAn inductive proof of this generalized method is given which\nsubsumes special cases, such as methods of zero- and infinite-value\ntime constants. Several important and useful corollaries of this\nmethod are discussed and several examples are analyzed.", "doi": "10.1109/TCSI.2009.2030092", "issn": "0098-4094", "publisher": "IEEE", "publication": "IEEE Transactions on Circuits and Systems", "publication_date": "2010-06", "series_number": "6", "volume": "57", "issue": "6", "pages": "1105-1121" }, { "id": "authors:mqgkf-zw453", "collection": "authors", "collection_id": "mqgkf-zw453", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20100126-111532019", "type": "article", "title": "An Octave-Range, Watt-Level, Fully-Integrated CMOS Switching Power Mixer Array for Linearization and Back-Off-Efficiency Improvement", "author": [ { "family_name": "Kousai", "given_name": "Shouhei", "clpid": "Kousai-S" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "The power mixer array is presented as a novel power generation approach for non-constant envelope signals. It comprises several power mixer units that are dynamically turned on and off to improve the linearity and back-off efficiency. At the circuit level, the power mixer unit can operate as a switching amplifier to achieve high peak power efficiency. Additional circuit level linearization and back-off efficiency improvement techniques are also proposed. To demonstrate the feasibility of this idea, a fully-integrated octave-range CMOS power mixer array is implemented in a 130 nm CMOS process. It is operational between 1.2 GHz and 2.4 GHz and can generate an output power of +31.3 dBm into an external 50 \u03a9 load with a PAE of 42% and a gain compression of only 0.4 dB at 1.8 GHz. It achieves a PAE of 25%, at an average output power of +26.4 dBm, and an EVM of 4.6% with a non-constant-envelope 16 QAM signal. It can also produce arbitrary signal levels down to -70 dBm of output power with the 16 QAM-modulated signal without any RF gain control circuit.", "doi": "10.1109/JSSC.2009.2032271", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2009-12", "series_number": "12", "volume": "44", "issue": "12", "pages": "3376-3392" }, { "id": "authors:x0xfw-gdd47", "collection": "authors", "collection_id": "x0xfw-gdd47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090923-143136224", "type": "article", "title": "Analysis of Internally Bandlimited Multistage Cubic-Term Generators for RF Receivers", "author": [ { "family_name": "Keehr", "given_name": "Edward A.", "clpid": "Keehr-E-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Adaptive feedforward error cancellation applied to correct distortion arising from third-order nonlinearities in RF receivers requires low-noise low-power reference cubic nonidealities. Multistage cubic-term generators utilizing cascaded nonlinear operations are ideal in this regard, but the frequency response of the interstage circuitry can introduce errors into the cubing operation. In this paper, an overview of the use of cubic-term generators in receivers relative to other applications is presented. An interstage frequency response plan is presented for a receiver cubic-term generator and is shown to function for arbitrary three-signal third-order intermodulation generation. The noise of such circuits is also considered and is shown to depend on the total incoming signal power across a particular frequency band. Finally, the effects of the interstage group delay are quantified in the context of a relevant communication standard requirement.", "doi": "10.1109/TCSI.2008.2008282", "issn": "1549-8328", "publisher": "IEEE", "publication": "IEEE Transactions on Circuits and Systems I: Regular Papers", "publication_date": "2009-08", "series_number": "8", "volume": "56", "issue": "8", "pages": "1758-1771" }, { "id": "authors:s1x30-6b371", "collection": "authors", "collection_id": "s1x30-6b371", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090820-155012753", "type": "article", "title": "A Spectral-Scanning Nuclear Magnetic Resonance Imaging (MRI) Transceiver", "author": [ { "family_name": "Hassibi", "given_name": "Arjang", "clpid": "Hassibi-A" }, { "family_name": "Babakhani", "given_name": "Aydin", "clpid": "Babakhani-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "An integrated spectral-scanning nuclear magnetic resonance imaging (MRI) transceiver is implemented in a 0.12 mum SiGe BiCMOS process. The MRI transmitter and receiver circuitry is designed specifically for small-scale surface MRI diagnostics applications where creating low (below 1 T) and inhomogeneous magnetic field is more practical. The operation frequency for magnetic resonance detection and analysis is tunable from 1 kHz to 37 MHz, corresponding to 0-0.9 T magnetization for ^1H (hydrogen). The concurrent measurement bandwidth is approximately one frequency octave. The chip can also be used for conventional narrowband nuclear magnetic resonance (NMR) spectroscopy from 1 kHz up to 250 MHz. This integrated transceiver consists of both the magnetic resonance transmitter which generates the required excitation pulses for the magnetic dipole excitation, and the receiver which recovers the responses of the dipoles.", "doi": "10.1109/JSSC.2009.2020456", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2009-06", "series_number": "6", "volume": "44", "issue": "6", "pages": "1805-1813" }, { "id": "authors:zcpj0-06e93", "collection": "authors", "collection_id": "zcpj0-06e93", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20090421-112006759", "type": "article", "title": "Near-field direct antenna modulation", "author": [ { "family_name": "Babakhani", "given_name": "Aydin", "clpid": "Babakhani-A" }, { "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" } ], "abstract": "NFDAM systems provide a unique solution for transmitting highly secured direction-dependent data and hence preventing eavesdroppers from properly demodulating the signal. A 60-GHz proof-of-concept chip was designed and measured.", "doi": "10.1109/MMM.2008.930674", "issn": "1527-3342", "publisher": "IEEE", "publication": "IEEE Microwave Magazine", "publication_date": "2009-02", "series_number": "1", "volume": "10", "issue": "1", "pages": "36-46" }, { "id": "authors:s6wg7-cwz33", "collection": "authors", "collection_id": "s6wg7-cwz33", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:JEOieeejssc08", "type": "article", "title": "A Scalable 6-to-18 GHz Concurrent Dual-Band Quad-Beam Phased-Array Receiver in CMOS", "author": [ { "family_name": "Jeon", "given_name": "Sanggeun", "clpid": "Jeon-Sanggeun" }, { "family_name": "Wang", "given_name": "Yu-Jiu", "clpid": "Wang-Yu-Jiu" }, { "family_name": "Wang", "given_name": "Hua", "clpid": "Wang-Hua" }, { "family_name": "Bohn", "given_name": "Florian", "clpid": "Bohn-F" }, { "family_name": "Natarajan", "given_name": "Arun", "orcid": "0000-0003-3648-3844", "clpid": "Natarajan-A" }, { "family_name": "Babakhani", "given_name": "Aydin", "clpid": "Babakhani-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "This paper reports a 6-to-18 GHz integrated phased- array receiver implemented in 130-nm CMOS. The receiver is easily scalable to build a very large-scale phased-array system. It concurrently forms four independent beams at two different frequencies from 6 to 18 GHz. The nominal conversion gain of the receiver ranges from 16 to 24 dB over the entire band while the worst-case cross-band and cross-polarization rejections are achieved 48 dB and 63 dB, respectively. Phase shifting is performed in the LO path by a digital phase rotator with the worst-case RMS phase error and amplitude variation of 0.5\u00b0 and 0.4 dB, respectively, over the entire band. A four-element phased-array receiver system is implemented based on four receiver chips. The measured array patterns agree well with the theoretical ones with a peak-to-null ratio of over 21.5 dB.", "doi": "10.1109/JSSC.2008.2004863", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2008-12", "series_number": "12", "volume": "43", "issue": "12", "pages": "2660-2673" }, { "id": "authors:76wk5-85j38", "collection": "authors", "collection_id": "76wk5-85j38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BABieeejssc08", "type": "article", "title": "Transmitter Architectures Based on Near-Field Direct Antenna Modulation", "author": [ { "family_name": "Babakhani", "given_name": "Aydin", "clpid": "Babakhani-A" }, { "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" } ], "abstract": "A near-field direct antenna modulation (NFDAM) technique is 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. Near-field direct antenna modulation (NFDAM) can be performed by using either switches or varactors. Two fully-integrated proof-of-concept NFDAM transmitters operating at 60 GHz using switches and varactors are demonstrated in silicon proving the feasibility of this approach.", "doi": "10.1109/JSSC.2008.2004864", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2008-12", "series_number": "12", "volume": "43", "issue": "12", "pages": "2674-2692" }, { "id": "authors:31z59-nkp44", "collection": "authors", "collection_id": "31z59-nkp44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:AOKieeejscc08", "type": "article", "title": "A Fully-Integrated Quad-Band GSM/GPRS CMOS Power Amplifier", "author": [ { "family_name": "Aoki", "given_name": "Ichiro", "clpid": "Aoki-I" }, { "family_name": "Kee", "given_name": "Scott", "clpid": "Kee-S-D" }, { "family_name": "Magoon", "given_name": "Rahul", "clpid": "Magoon-R" }, { "family_name": "Aparicio", "given_name": "Roberto", "clpid": "Aparicio-R" }, { "family_name": "Bohn", "given_name": "Florian", "clpid": "Bohn-F" }, { "family_name": "Zachan", "given_name": "Jeff", "clpid": "Zachan-J" }, { "family_name": "Hatcher", "given_name": "Geoff", "clpid": "Hatcher-G" }, { "family_name": "McClymont", "given_name": "Donald", "clpid": "McClymont-D" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Concentric distributed active transformers (DAT) are used to implement a fully-integrated quad-band power amplifier (PA) in a standard 130 nm CMOS process. The DAT enables the power amplifier to integrate the input and output matching networks on the same silicon die. The PA integrates on-chip closed-loop power control and operates under supply voltages from 2.9 V to 5.5 V in a standard micro-lead-frame package. It shows no oscillations, degradation, or failures for over 2000 hours of operation with a supply of 6 V at 135\u00b0 under a VSWR of 15:1 at all phase angles and has also been tested for more than 2 million device-hours (with ongoing reliability monitoring) without a single failure under nominal operation conditions. It produces up to +35 dBm of RF power with power-added efficiency of 51%.", "doi": "10.1109/JSSC.2008.2004870", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2008-12", "series_number": "12", "volume": "43", "issue": "12", "pages": "2747-2758" }, { "id": "authors:v7p5x-8v926", "collection": "authors", "collection_id": "v7p5x-8v926", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:KEEieeejssc08", "type": "article", "title": "Equalization of Third-Order Intermodulation Products in Wideband Direct Conversion Receivers", "author": [ { "family_name": "Keehr", "given_name": "Edward A.", "clpid": "Keehr-E-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "This paper reports a SAW-less direct-conversion receiver which utilizes a mixed-signal feedforward path to regenerate and adaptively cancel IM3 products, thus accomplishing system-level linearization. The receiver system performance is dominated by a custom integrated RF front end implemented in 130-nm CMOS and achieves an uncorrected out-of-band IIP3 of -7.1 dBm under the worst-case UMTS FDD Region 1 blocking specifications. Under IM3 equalization, the receiver achieves an effective IIP3 of +5.3 dBm and meets the UMTS BER sensitivity requirement with 3.7 dB of margin.", "doi": "10.1109/JSSC.2008.2005701", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2008-12", "series_number": "12", "volume": "43", "issue": "12", "pages": "2853-2867" }, { "id": "authors:85zj7-6yq66", "collection": "authors", "collection_id": "85zj7-6yq66", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:AFSieeetcasI08", "type": "article", "title": "Ultrafast Analog Fourier Transform Using 2-D LC Lattice", "author": [ { "family_name": "Afshari", "given_name": "Ehsan", "clpid": "Afshari-E" }, { "family_name": "Bhat", "given_name": "Harish S.", "orcid": "0000-0001-7631-1831", "clpid": "Bhat-Harish-Subrahmanya" }, { "family_name": "Hajimiri", "given_name": "S. A. (Ali)", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "We describe how a 2-D rectangular lattice of inductors and capacitors can serve as an analog Fourier transform device, generating an approximate discrete Fourier transform (DFT) of an arbitrary input vector of fixed length. The lattice displays diffractive and refractive effects and mimics the combined optical effects of a thin-slit aperture and lens. Diffraction theories in optics are usually derived for 3-D media, whereas our derivations proceed in 2-D. Analytical and numerical results show agreement between lattice output and the true DFT. Potentially, this lattice can be used for an extremely low latency and high throughput analog signal processing device. The lattice can be fabricated on-chip with frequency of operation of more than 10 GHz.", "doi": "10.1109/TCSI.2008.918151", "issn": "1549-8328", "publisher": "IEEE", "publication": "IEEE Transactions on Circuits and Systems I: Regular Papers", "publication_date": "2008-09", "series_number": "8", "volume": "55", "issue": "8", "pages": "2332-2343" }, { "id": "authors:hxrdz-nx558", "collection": "authors", "collection_id": "hxrdz-nx558", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20171103-120941255", "type": "article", "title": "A self-sustaining ultrahigh-frequency nanoelectromechanical oscillator", "author": [ { "family_name": "Feng", "given_name": "X. L.", "clpid": "Feng-X-L" }, { "family_name": "White", "given_name": "C. J.", "clpid": "White-C-J" }, { "family_name": "Hajimiri", "given_name": "A.", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Roukes", "given_name": "M. L.", "orcid": "0000-0002-2916-6026", "clpid": "Roukes-M-L" } ], "abstract": "Sensors based on nanoelectromechanical systems vibrating at high and ultrahigh frequencies are capable of levels of performance that surpass those of larger sensors. Nanoelectromechanical devices have achieved unprecedented sensitivity in the detection of displacement, mass, force and charge. To date, these milestones have been achieved with passive devices that require external periodic or impulsive stimuli to excite them into resonance. Here, we demonstrate an autonomous and self-sustaining nanoelectromechanical oscillator that generates continuous ultrahigh-frequency signals when powered by a steady d.c. source. The frequency-determining element in the oscillator is a 428 MHz nanoelectromechanical resonator that is embedded within a tunable electrical feedback network to generate active and stable self-oscillation. Our prototype nanoelectromechanical oscillator exhibits excellent frequency stability, linewidth narrowing and low phase noise performance. Such ultrahigh-frequency oscillators provide a comparatively simple means for implementing a wide variety of practical sensing applications. They also offer intriguing opportunities for nanomechanical frequency control, timing and synchronization.", "doi": "10.1038/nnano.2008.125", "issn": "1748-3387", "publisher": "Nature Publishing Group", "publication": "Nature Nanotechnology", "publication_date": "2008-06", "series_number": "6", "volume": "3", "issue": "6", "pages": "342-346" }, { "id": "authors:8vcv1-ebz23", "collection": "authors", "collection_id": "8vcv1-ebz23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HASjap07", "type": "article", "title": "On noise processes and limits of performance in biosensors", "author": [ { "family_name": "Hassibi", "given_name": "Arjang", "clpid": "Hassibi-A" }, { "family_name": "Vikalo", "given_name": "Haris", "clpid": "Vikalo-H" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "In this paper, we present a comprehensive stochastic model describing the measurement uncertainty, output signal, and limits of detection of affinity-based biosensors. The biochemical events within the biosensor platform are modeled by a Markov stochastic process, describing both the probabilistic mass transfer and the interactions of analytes with the capturing probes. To generalize this model and incorporate the detection process, we add noisy signal transduction and amplification stages to the Markov model. Using this approach, we are able to evaluate not only the output signal and the statistics of its fluctuation but also the noise contributions of each stage within the biosensor platform. Furthermore, we apply our formulations to define the signal-to-noise ratio, noise figure, and detection dynamic range of affinity-based biosensors. Motivated by the platforms encountered in practice, we construct the noise model of a number of widely used systems. The results of this study show that our formulations predict the behavioral characteristics of affinity-based biosensors which indicate the validity of the model.", "doi": "10.1063/1.2748624", "issn": "0021-8979", "publisher": "Journal of Applied Physics", "publication": "Journal of Applied Physics", "publication_date": "2007-07-01", "series_number": "1", "volume": "102", "issue": "1", "pages": "Art. No. 014909" }, { "id": "authors:f0x0c-byt70", "collection": "authors", "collection_id": "f0x0c-byt70", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:MANieeejssc07", "type": "article", "title": "A Breakdown Voltage Multiplier for High Voltage Swing Drivers", "author": [ { "family_name": "Mandegaran", "given_name": "Sam", "clpid": "Mandegaran-S" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A novel breakdown voltage (BV) multiplier is introduced that makes it possible to generate high output voltage swings using transistors with low breakdown voltages. The timing analysis of the stage is used to optimize its dynamic response. A 10 Gb/s optical modulator driver with a differential output voltage swing of 8 V on a 50 \u03a9 load was implemented in a SiGe BiCMOS process. It uses the BV-Doubler topology to achieve output swings twice the collector\u2013emitter breakdown voltage without stressing any single transistor.", "doi": "10.1109/JSSC.2006.889390", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2007-02-01", "series_number": "2", "volume": "42", "issue": "2", "pages": "302-312" }, { "id": "authors:hm5yw-sg109", "collection": "authors", "collection_id": "hm5yw-sg109", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:ROKapl06", "type": "article", "title": "Brownian noise in radiation-pressure-driven micromechanical oscillators", "author": [ { "family_name": "Rokhsari", "given_name": "Hossein", "clpid": "Rokhsari-H" }, { "family_name": "Hossein-Zadeh", "given_name": "Mani", "clpid": "Hossein-Zadeh-M" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Vahala", "given_name": "Kerry", "orcid": "0000-0003-1783-1380", "clpid": "Vahala-K-J" } ], "abstract": "The authors demonstrate Brownian-noise-limited operation of an optomechanical oscillator, wherein mechanical oscillations of a silica optical microcavity are sustained by means of radiation pressure. Using phase noise measurement above threshold, it has been shown that the short-term linewidth of mechanical oscillations is fundamentally broadened, limited by thermal equipartition of energy.", "doi": "10.1063/1.2424276", "issn": "0003-6951", "publisher": "Applied Physics Letters", "publication": "Applied Physics Letters", "publication_date": "2006-12-25", "series_number": "26", "volume": "89", "issue": "26", "pages": "Art. No. 261109" }, { "id": "authors:97vsz-v9y28", "collection": "authors", "collection_id": "97vsz-v9y28", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BABieeejssc06", "type": "article", "title": "A 77-GHz Phased-Array Transceiver With On-Chip Antennas in Silicon: Receiver and Antennas", "author": [ { "family_name": "Babakhani", "given_name": "Aydin", "clpid": "Babakhani-A" }, { "family_name": "Guan", "given_name": "Xiang", "clpid": "Guan-X" }, { "family_name": "Komijani", "given_name": "Abbas", "clpid": "Komijani-A" }, { "family_name": "Natarajan", "given_name": "Arun", "orcid": "0000-0003-3648-3844", "clpid": "Natarajan-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "In this paper, we 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 +2 dBi.", "doi": "10.1109/JSSC.2006.884811", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2006-12-01", "series_number": "12", "volume": "41", "issue": "12", "pages": "2795-2806" }, { "id": "authors:3as2h-k1z76", "collection": "authors", "collection_id": "3as2h-k1z76", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:NATieeejssc06", "type": "article", "title": "A 77-GHz Phased-Array Transceiver With On-Chip Antennas in Silicon: Transmitter and Local LO-Path Phase Shifting", "author": [ { "family_name": "Natarajan", "given_name": "Arun", "orcid": "0000-0003-3648-3844", "clpid": "Natarajan-A" }, { "family_name": "Komijani", "given_name": "Abbas", "clpid": "Komijani-A" }, { "family_name": "Guan", "given_name": "Xiang", "clpid": "Guan-X" }, { "family_name": "Babakhani", "given_name": "Aydin", "clpid": "Babakhani-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Integration of mm-wave multiple-antenna systems on silicon-based processes enables complex, low-cost systems for high-frequency communication and sensing applications. In this paper, the transmitter and LO-path phase-shifting sections of the first fully integrated 77-GHz phased-array transceiver are presented. The SiGe transceiver utilizes a local LO-path phase-shifting architecture to achieve beam steering and includes four transmit and receive elements, 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 element of the heterodyne transmitter generates +12.5 dBm of output power at 77 GHz with a bandwidth of 2.5 GHz leading to a 4-element effective isotropic radiated power (EIRP) of 24.5 dBm. Each on-chip PA has a maximum saturated power of +17.5 dBm at 77 GHz. The phased-array performance is measured using an internal test option and achieves 12-dB peak-to-null ratio with two transmit and receive elements active.", "doi": "10.1109/JSSC.2006.884817", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2006-12-01", "series_number": "12", "volume": "41", "issue": "12", "pages": "2807-2819" }, { "id": "authors:0aw3h-0yx83", "collection": "authors", "collection_id": "0aw3h-0yx83", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BUCieeemtt06", "type": "article", "title": "An Integrated Subharmonic Coupled-Oscillator Scheme for a 60-GHz Phased-Array Transmitter", "author": [ { "family_name": "Buckwalter", "given_name": "James F.", "clpid": "Buckwalter-J-F" }, { "family_name": "Babakhani", "given_name": "Aydin", "clpid": "Babakhani-A" }, { "family_name": "Komijani", "given_name": "Abbas", "clpid": "Komijani-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "This paper describes the design of an integrated coupled-oscillator array in SiGe for millimeter-wave applications. The design focuses on a scalable radio architecture where multiple dies are tiled to form larger arrays. A 2 \u00d7 2 oscillator array for a 60-GHz transmitter is fabricated with integrated power amplifiers and on-chip antennas. To lock between multiple dies, an injection-locking scheme appropriate for wire-bond interconnects is described. The 2 \u00d7 2 array demonstrates a 200\u2013MHz locking range and 1 \u00d7 4 array formed by two adjacent chips has a 60-MHz locking range. The phase noise of the coupled oscillators is below 100 dBc/Hz at a 1-MHz offset when locked to an external reference. To the best of the authors' knowledge, this is the highest frequency demonstration of coupled oscillators fabricated in a conventional silicon integrated-circuit process.", "doi": "10.1109/TMTT.2006.885581", "issn": "0018-9480", "publisher": "IEEE", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2006-12", "series_number": "12, Pa", "volume": "54", "issue": "12, Pa", "pages": "4271-4280" }, { "id": "authors:r8yn2-dwb31", "collection": "authors", "collection_id": "r8yn2-dwb31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:KOMieeejssc06", "type": "article", "title": "A Wideband 77-GHz, 17.5-dBm Fully Integrated Power Amplifier in Silicon", "author": [ { "family_name": "Komijani", "given_name": "Abbas", "clpid": "Komijani-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A 77-GHz, +17.5 dBm power amplifier (PA) with fully integrated 50-\u03a9 input and output matching and fabricated in a 0.12-\u00b5m SiGe BiCMOS process is presented. The PA achieves a peak power gain of 17 dB and a maximum single-ended output power of 17.5 dBm with 12.8% of power-added efficiency (PAE). It has a 3-dB bandwidth of 15 GHz and draws 165 mA from a 1.8-V supply. Conductor-backed coplanar waveguide (CBCPW) is used as the transmission line structure resulting in large isolation between adjacent lines, enabling integration of the PA in an area of 0.6 mm^2. By using a separate image-rejection filter incorporated before the PA, the rejection at IF frequency of 25 GHz is improved by 35 dB, helping to keep the PA design wideband.", "doi": "10.1109/JSSC.2006.877258", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2006-08-01", "series_number": "8", "volume": "41", "issue": "8", "pages": "1749-1756" }, { "id": "authors:mr37j-f1w31", "collection": "authors", "collection_id": "mr37j-f1w31", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HOSpra06", "type": "article", "title": "Characterization of a radiation-pressure-driven micromechanical oscillator", "author": [ { "family_name": "Hossein-Zadeh", "given_name": "Mani", "clpid": "Hossein-Zadeh-M" }, { "family_name": "Rokhsari", "given_name": "Hossein", "clpid": "Rokhsari-H" }, { "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" } ], "abstract": "We present for the first time a detailed experimental study of the oscillation frequency, linewidth, RF spectrum and the phase noise of a radiation-pressure-driven micromechanical oscillator in a microtoroid geometry. Through this study we identify the critical parameters for optimal operation of this device and derive key expressions for tailoring the desired characteristics. The outcome of this study paves the ground for exploiting this unique phenomenon in photonic systems as well as fundamental studies in macroscopic quantum mechanics.", "doi": "10.1103/PhysRevA.74.023813", "issn": "1050-2947", "publisher": "Physical Review A", "publication": "Physical Review A", "publication_date": "2006-08-01", "series_number": "2", "volume": "74", "issue": "2", "pages": "Art. No. 023813" }, { "id": "authors:1g0w3-bf512", "collection": "authors", "collection_id": "1g0w3-bf512", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BUCieeejssc06c", "type": "article", "title": "Phase and amplitude pre-emphasis techniques for low-power serial links", "author": [ { "family_name": "Buckwalter", "given_name": "James F.", "clpid": "Buckwalter-J-F" }, { "family_name": "Meghelli", "given_name": "Mounir", "clpid": "Meghelli-M" }, { "family_name": "Friedman", "given_name": "Daniel J.", "clpid": "Friedman-D-J" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A novel approach to equalization of high-speed serial links combines both amplitude pre-emphasis to correct for intersymbol interference and phase pre-emphasis to compensate for deterministic jitter, in particular, data-dependent jitter. Phase pre-emphasis augments the performance of low power transmitters in bandwidth-limited channels. The transmitter circuit is implemented in a 90-nm bulk CMOS process and reduces power consumption by pushing CMOS static logic to the output stage, a 4:1 output multiplexer. The received signal jitter over a cable is reduced from 16.15 ps to 10.29 ps with only phase pre-emphasis at the transmitter. The jitter is reduced by 3.6 ps over an FR-4 backplane interconnect. A transmitter without phase pre-emphasis consumes 18 mW of power at 6Gb/s and 600mVpp output swing, a power budget of 3mW/Gb/s, while a transmitter with phase pre-emphasis consumes 24mW, a budget of 4 mW/Gb/s.", "doi": "10.1109/JSSC.2006.874270", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2006-06-01", "series_number": "6", "volume": "41", "issue": "6", "pages": "1391-1399" }, { "id": "authors:7ee3s-sf944", "collection": "authors", "collection_id": "7ee3s-sf944", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:AFSjap06", "type": "article", "title": "Extremely wideband signal shaping using one- and two-dimensional nonuniform nonlinear transmission lines", "author": [ { "family_name": "Afshari", "given_name": "E.", "clpid": "Afshari-E" }, { "family_name": "Bhat", "given_name": "H. S.", "clpid": "Bhat-H-S" }, { "family_name": "Hajimiri", "given_name": "A.", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Marsden", "given_name": "J. E.", "clpid": "Marsden-J-E" } ], "abstract": "We propose a class of electrical circuits for extremely wideband (EWB) signal shaping. A one-dimensional, nonlinear, nonuniform transmission line is proposed for narrow pulse generation. A two-dimensional transmission lattice is proposed for EWB signal combining. Model equations for the circuits are derived. Theoretical and numerical solutions of the model equations are presented, showing that the circuits can be used for the desired application. The procedure by which the circuits are designed exemplifies a modern, mathematical design methodology for EWB circuits.", "doi": "10.1063/1.2174126", "issn": "0021-8979", "publisher": "Journal of Applied Physics", "publication": "Journal of Applied Physics", "publication_date": "2006-03-01", "series_number": "5", "volume": "99", "issue": "5", "pages": "Art. No. 054901" }, { "id": "authors:994c0-rvk50", "collection": "authors", "collection_id": "994c0-rvk50", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BUCieeejssc06b", "type": "article", "title": "Cancellation of crosstalk-induced jitter", "author": [ { "family_name": "Buckwalter", "given_name": "James F.", "clpid": "Buckwalter-J-F" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A novel jitter equalization circuit is presented that addresses crosstalk-induced jitter in high-speed serial links. A simple model of electromagnetic coupling demonstrates the generation of crosstalk-induced jitter. The analysis highlights unique aspects of crosstalk-induced jitter that differ from far-end crosstalk. The model is used to predict the crosstalk-induced jitter in 2-PAM and 4-PAM, which is compared to measurement. Furthermore, the model suggests an equalizer that compensates for the data-induced electromagnetic coupling between adjacent links and is suitable for pre- or post-emphasis schemes. The circuits are implemented using 130-nm MOSFETs and operate at 5-10 Gb/s. The results demonstrate reduced deterministic jitter and lower bit-error rate (BER). At 10 Gb/s, the crosstalk-induced jitter equalizer opens the eye at 10^sup-12 BER from 17 to 45 ps and lowers the rms jitter from 8.7 to 6.3 ps.", "doi": "10.1109/JSSC.2005.864113", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2006-03-01", "series_number": "3", "volume": "41", "issue": "3", "pages": "621-632" }, { "id": "authors:jq1pe-gvw12", "collection": "authors", "collection_id": "jq1pe-gvw12", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BUCieeejssc06a", "type": "article", "title": "Analysis and equalization of data-dependent jitter", "author": [ { "family_name": "Buckwalter", "given_name": "James F.", "clpid": "Buckwalter-J-F" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Data-dependent jitter limits the bit-error rate (BER) performance of broadband communication systems and aggravates synchronization in phase- and delay-locked loops used for data recovery. A method for calculating the data-dependent jitter in broadband systems from the pulse response is discussed. The impact of jitter on conventional clock and data recovery circuits is studied in the time and frequency domain. The deterministic nature of data-dependent jitter suggests equalization techniques suitable for high-speed circuits. Two equalizer circuit implementations are presented. The first is a SiGe clock and data recovery circuit modified to incorporate a deterministic jitter equalizer. This circuit demonstrates the reduction of jitter in the recovered clock. The second circuit is a MOS implementation of a jitter equalizer with independent control of the rising and falling edge timing. This equalizer demonstrates improvement of the timing margins that achieve 10/sup -12/ BER from 30 to 52 ps at 10 Gb/s.", "doi": "10.1109/JSSC.2005.864119", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2006-03-01", "series_number": "3", "volume": "41", "issue": "3", "pages": "607-620" }, { "id": "authors:6mv16-pms15", "collection": "authors", "collection_id": "6mv16-pms15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:ANAieeejssc05", "type": "article", "title": "A 10-Gb/s two-dimensional eye-opening monitor in 0.13-\u03bcm standard CMOS", "author": [ { "family_name": "Analui", "given_name": "Behnam", "clpid": "Analui-B" }, { "family_name": "Rylyakov", "given_name": "Alexander", "clpid": "Rylyakov-A" }, { "family_name": "Rylov", "given_name": "Sergey", "clpid": "Rylov-S" }, { "family_name": "Meghelli", "given_name": "Mounir", "clpid": "Meghelli-M" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "An eye-opening monitor (EOM) architecture that can capture a two-dimensional (2-D) map of the eye diagram of a high-speed data signal has been developed. Two single-quadrant phase rotators and one digital-to-analog converter (DAC) are used to generate rectangular masks with variable sizes and aspect ratios. Each mask is overlapped with the received eye diagram and the number of signal transitions inside the mask is recorded as error. The combination of rectangular masks with the same error creates error contours that overall provide a 2-D map of the eye. The authors have implemented a prototype circuit in 0.13-\u03bcm standard CMOS technology that operates up to 12.5 Gb/s at 1.2-V supply. The EOM maps the input eye to a 2-D error diagram with up to 68-dB mask error dynamic range. The left and right halves of the eyes are monitored separately to capture horizontally asymmetric eyes. The chip consumes 330 mW and operates reliably with supply voltages as low as 1 V at 10 Gb/s. The authors also present a detailed analysis that verifies if the measurements are in good agreement with the expected results.", "doi": "10.1109/JSSC.2005.856576", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2005-12-01", "series_number": "12", "volume": "40", "issue": "12", "pages": "2689-2699" }, { "id": "authors:0r82e-jjk94", "collection": "authors", "collection_id": "0r82e-jjk94", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:NATieeejssc05", "type": "article", "title": "A fully integrated 24-GHz phased-array transmitter in CMOS", "author": [ { "family_name": "Natarajan", "given_name": "Arun", "orcid": "0000-0003-3648-3844", "clpid": "Natarajan-A" }, { "family_name": "Komijani", "given_name": "Abbas", "clpid": "Komijani-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "This paper presents the first fully integrated 24-GHz phased-array transmitter designed using 0.18-/spl mu/m CMOS transistors. The four-element array includes four on-chip CMOS power amplifiers, with outputs matched to 50 /spl Omega/, that are each capable of generating up to 14.5 dBm of output power at 24 GHz. The heterodyne transmitter has a two-step quadrature up-conversion architecture with local oscillator (LO) frequencies of 4.8 and 19.2 GHz, which are generated by an on-chip frequency synthesizer. Four-bit LO path phase shifting is implemented in each element at 19.2 GHz, and the transmitter achieves a peak-to-null ratio of 23 dB with raw beam-steering resolution of 7/spl deg/ for radiation normal to the array. The transmitter can support data rates of 500 Mb/s on each channel (with BPSK modulation) and occupies 6.8 mm /spl times/ 2.1 mm of die area.", "doi": "10.1109/JSSC.2005.857420", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2005-12-01", "series_number": "12", "volume": "40", "issue": "12", "pages": "2502-2514" }, { "id": "authors:nnnqm-vcb56", "collection": "authors", "collection_id": "nnnqm-vcb56", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:ANAieeetmtt05", "type": "article", "title": "Data-dependent jitter in serial communications", "author": [ { "family_name": "Analui", "given_name": "Behnam", "clpid": "Analui-B" }, { "family_name": "Buckwalter", "given_name": "James F.", "clpid": "Buckwalter-J-F" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "We present a method for predicting data-dependent jitter (DDJ) introduced by a general linear time-invariant LTI system based on the system's unit step response. We express the exact DDJ of a first-order system and verify the validity of the solution experimentally. We then propose a perturbation technique to generalize the analytical expression for DDJ. We highlight the significance of the unit step response in characterizing DDJ and emphasize that bandwidth is not a complete measure for predicting DDJ. We separate the individual jitter contributions of prior bits and use the result to predict the DDJ of a general LTI system. In particular, we identify a dominant prior bit that signifies the well-known distribution of deterministic jitter, the two impulse functions. We also show a jitter minimization property of high-order LTI systems. We verify our generalized analytical expression of DDJ for several real systems including an integrated CMOS 10-Gb/s trans-impedance amplifier by comparing the theory and measurement results. The theory predicts the jitter with as low as only 7.5% error.", "doi": "10.1109/TMTT.2005.857118", "issn": "0018-9480", "publisher": "IEEE Transactions on Microwave Theory and Techniques", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2005-11-01", "series_number": "11", "volume": "53", "issue": "11", "pages": "3388-3397" }, { "id": "authors:y535t-n5g32", "collection": "authors", "collection_id": "y535t-n5g32", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:KOMieeejssc05", "type": "article", "title": "A 24-GHz, +14.5-dBm fully integrated power amplifier in 0.18-\u03bcm CMOS", "author": [ { "family_name": "Komijani", "given_name": "Abbas", "clpid": "Komijani-A" }, { "family_name": "Natarajan", "given_name": "Arun", "orcid": "0000-0003-3648-3844", "clpid": "Natarajan-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A 24-GHz +14.5-dBm fully integrated power amplifier with on-chip 50-[ohm] input and output matching is demonstrated in 0.18-\u03bcm CMOS. The use of substrate-shielded coplanar waveguide structures for matching networks results in low passive loss and small die size. Simple circuit techniques based on stability criteria derived result in an unconditionally stable amplifier. The power amplifier achieves a power gain of 7 dB and a maximum single-ended output power of +14.5-dBm with a 3-dB bandwidth of 3.1 GHz, while drawing 100 mA from a 2.8-V supply. The chip area is 1.26 mm^2.", "doi": "10.1109/JSSC.2005.848143", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2005-09-01", "series_number": "9", "volume": "4", "issue": "9", "pages": "1901-1908" }, { "id": "authors:znn24-h0k29", "collection": "authors", "collection_id": "znn24-h0k29", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HAJprocieee05", "type": "article", "title": "Integrated phased array systems in silicon", "author": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Hashemi", "given_name": "Hossein", "clpid": "Hashemi-H" }, { "family_name": "Natarajan", "given_name": "Arun", "orcid": "0000-0003-3648-3844", "clpid": "Natarajan-A" }, { "family_name": "Guan", "given_name": "Xiang", "clpid": "Guan-X" }, { "family_name": "Komijani", "given_name": "Abbas", "clpid": "Komijani-A" } ], "abstract": "Silicon offers a new set of possibilities and challenges for RF, microwave, and millimeter-wave applications. While the high cutoff frequencies of the SiGe heterojunction bipolar transistors and the ever-shrinking feature sizes of MOSFETs hold a lot of promise, new design techniques need to be devised to deal with the realities of these technologies, such as low breakdown voltages, lossy substrates, low-Q passives, long interconnect parasitics, and high-frequency coupling issues. As an example of complete system integration in silicon, this paper presents the first fully integrated 24-GHz eight-element phased array receiver in 0.18-\u03bcm silicon-germanium and the first fully integrated 24-GHz four-element phased array transmitter with integrated power amplifiers in 0.18-\u03bcm CMOS. The transmitter and receiver are capable of beam forming and can be used for communication, ranging, positioning, and sensing applications.", "doi": "10.1109/JPROC.2005.852231", "issn": "0018-9219", "publisher": "Proceedings of the IEEE", "publication": "Proceedings of the IEEE", "publication_date": "2005-09-01", "series_number": "9", "volume": "93", "issue": "9", "pages": "1637-1655" }, { "id": "authors:4z3fg-21j15", "collection": "authors", "collection_id": "4z3fg-21j15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:ANAieeetcsII05", "type": "article", "title": "Instantaneous Clockless Data Recovery and Demultiplexing", "author": [ { "family_name": "Analui", "given_name": "Behnam", "clpid": "Analui-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "An alternative architecture for instantaneous data recovery for burst-mode communication is introduced. The architecture can perform 1:n demultiplexing without additional clock recovery phase-locked loop or sampling blocks. A finite-state machine (FSM) is formed with combinational logic and analog LC transmission line delay cells in a feedback loop. The FSM responds to input data transitions instantaneously and sets the outputs. The system reduces unit interval jitter by a factor of n. The new architecture is demonstrated via a SiGe 1:2 clockless demultiplexer circuit that operates at 7.5 Gb/s.", "doi": "10.1109/TCSII.2005.850453", "issn": "1549-7747", "publisher": "IEEE", "publication": "IEEE Transactions on Circuits and Systems II: Express Briefs", "publication_date": "2005-08", "series_number": "8", "volume": "52", "issue": "8", "pages": "437-441" }, { "id": "authors:q69fw-36m49", "collection": "authors", "collection_id": "q69fw-36m49", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:AFSieeejssc05", "type": "article", "title": "Nonlinear transmission lines for pulse shaping in silicon", "author": [ { "family_name": "Afshari", "given_name": "Ehsan", "clpid": "Afshari-E" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Nonlinear transmission lines (NLTL) are used for pulse shaping. We developed the theory of pulse propagation through the NLTL. The problem of a wide pulse degenerating into multiple pulses rather than a single pulse is solved by using a gradually scaled NLTL. We exploit certain favorable properties of accumulation-mode MOS varactors to design an NLTL that can simultaneously sharpen both rising and falling edges. There is a good agreement among the theory, simulations, and measurements.", "doi": "10.1109/JSSC.2005.843639", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2005-03-01", "series_number": "3", "volume": "40", "issue": "3", "pages": "744-752" }, { "id": "authors:hkwze-e7k27", "collection": "authors", "collection_id": "hkwze-e7k27", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HASieeetmtt05", "type": "article", "title": "A 24-GHz SiGe Phased-Array Receiver\u2014LO Phase-Shifting Approach", "author": [ { "family_name": "Hashemi", "given_name": "Hossein", "clpid": "Hashemi-H" }, { "family_name": "Guan", "given_name": "Xiang", "clpid": "Guan-X" }, { "family_name": "Komijani", "given_name": "Abbas", "clpid": "Komijani-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A local-oscillator phase-shifting approach is introduced to implement a fully integrated 24-GHz phased-array receiver using an SiGe technology. Sixteen phases of the local oscillator are generated in one oscillator core, resulting in a raw beam-forming accuracy of 4 bits. These phases are distributed to all eight receiving paths of the array by a symmetric network. The appropriate phase for each path is selected using high-frequency analog multiplexers. The raw beam-steering resolution of the array is better than 10 [degrees] for a forward-looking angle, while the array spatial selectivity, without any amplitude correction, is better than 20 dB. The overall gain of the array is 61 dB, while the array improves the input signal-to-noise ratio by 9 dB.", "doi": "10.1109/TMTT.2004.841218", "issn": "0018-9480", "publisher": "IEEE Transactions on Microwave Theory and Techniques", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2005-02-01", "series_number": "2", "volume": "53", "issue": "2", "pages": "614-626" }, { "id": "authors:f55vb-c4j85", "collection": "authors", "collection_id": "f55vb-c4j85", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:GUAieeejssc04b", "type": "article", "title": "A Fully Integrated 24-GHz Eight-Element Phased-Array Receiver in Silicon", "author": [ { "family_name": "Guan", "given_name": "Xiang", "clpid": "Guan-X" }, { "family_name": "Hashemi", "given_name": "Hossein", "clpid": "Hashemi-H" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "This paper reports the first fully integrated 24-GHz eight-element phased-array receiver in a SiGe BiCMOS technology. The receiver utilizes a heterodyne topology and the signal combining is performed at an IF of 4.8 GHz. The phase-shifting with 4 bits of resolution is realized at the LO port of the first down-conversion mixer. A ring LC voltage-controlled oscillator (VCO) generates 16 different phases of the LO. An integrated 19.2-GHz frequency synthesizer locks the VCO frequency to a 75-MHz external reference. Each signal path achieves a gain of 43 dB, a noise figure of 7.4 dB, and an IIP3 of -11 dBm. The eight-path array achieves an array gain of 61 dB and a peak-to-null ratio of 20 dB and improves the signal-to-noise ratio at the output by 9 dB.", "doi": "10.1109/JSSC.2004.836339", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2004-12-01", "series_number": "12", "volume": "39", "issue": "12", "pages": "2311-2320" }, { "id": "authors:jr2qh-w6w38", "collection": "authors", "collection_id": "jr2qh-w6w38", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:BUCieeetcsII04", "type": "article", "title": "Predicting data-dependent jitter", "author": [ { "family_name": "Buckwalter", "given_name": "James", "clpid": "Buckwalter-J-F" }, { "family_name": "Analui", "given_name": "Behnam", "clpid": "Analui-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "An analysis for calculating data-dependent jitter (DDJ) in a first-order system is introduced. The predicted DDJ features unique threshold crossing times with self-similar geometry. An approximation for DDJ in second-order systems is described in terms of the damping factor and natural frequency. Higher order responses demonstrate conditions under which unique threshold crossing times do not exist and total jitter is minimized. The DDJ predictions are verified with jitter measurements in a bandwidth-limited amplifier. The predictions for both first and second-order systems anticipate the features of the observed jitter.", "doi": "10.1109/TCSII.2004.834537", "issn": "1549-7747", "publisher": "IEEE", "publication": "IEEE Transactions on Circuits and Systems II: Express Briefs", "publication_date": "2004-09", "series_number": "9", "volume": "51", "issue": "9", "pages": "453-457" }, { "id": "authors:5veaq-wz633", "collection": "authors", "collection_id": "5veaq-wz633", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HAJieeecm04", "type": "article", "title": "Phased Array Systems in Silicon", "author": [ { "family_name": "Hajimiri", "given_name": "A.", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Komijani", "given_name": "A.", "clpid": "Komijani-A" }, { "family_name": "Natarjan", "given_name": "A.", "orcid": "0000-0003-3648-3844", "clpid": "Natarajan-A" }, { "family_name": "Chunara", "given_name": "R.", "clpid": "Chunara-R" }, { "family_name": "Guan", "given_name": "X.", "clpid": "Guan-X" }, { "family_name": "Hashemi", "given_name": "H.", "clpid": "Hashemi-H" } ], "abstract": "Phased array systems, a special case of 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 article focuses on the architectural and circuit-level trade-offs involved in the design of the first silicon-based fully integrated phased array system operating at 24 GHz. The details of some of the important circuit building blocks are also discussed. The measured results demonstrate the feasibility of using integrated phased arrays for wireless communication and vehicular radar applications at 24 GHz.", "doi": "10.1109/MCOM.2004.1321403", "issn": "0163-6804", "publisher": "IEEE Communications Magazine", "publication": "IEEE Communications Magazine", "publication_date": "2004-08-01", "series_number": "8", "volume": "42", "issue": "8", "pages": "122-130" }, { "id": "authors:5bbzz-wx990", "collection": "authors", "collection_id": "5bbzz-wx990", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:ANAieeejssc04", "type": "article", "title": "Bandwidth Enhancement for Transimpedance Amplifiers", "author": [ { "family_name": "Analui", "given_name": "Behnam", "clpid": "Analui-B" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A technique for bandwidth enhancement of a given amplifier is presented. Adding several interstage passive matching networks enables the control of transfer function and frequency response behavior. Parasitic capacitances of cascaded gain stages are isolated from each other and absorbed into passive networks. A simplified design procedure, using well-known low-pass filter component values, is introduced. To demonstrate the feasibility of the method, a CMOS transimpedance amplifier (TIA) is implemented in a 0.18-\u03bcm BiCMOS technology. It achieves 3 dB bandwidth of 9.2 GHz in the presence of a 0.5-pF photodiode capacitance. This corresponds to a bandwidth enhancement ratio of 2.4 over the amplifier without the additional passive networks. The trans-resistance gain is 54 dB[ohm], while drawing 55 mA from a 2.5-V supply. The input sensitivity of the TIA is -18 dBm for a bit error rate of 10^-12.", "doi": "10.1109/JSSC.2004.831783", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2004-08-01", "series_number": "8", "volume": "39", "issue": "8", "pages": "1263-1270" }, { "id": "authors:d7m7z-82693", "collection": "authors", "collection_id": "d7m7z-82693", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:GUAieeejssc04a", "type": "article", "title": "A 24-GHz CMOS Front-End", "author": [ { "family_name": "Guan", "given_name": "Xiang", "clpid": "Guan-X" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "This paper reports the first 24-GHz CMOS front-end in a 0.18-\u00b5m process. It consists of a low-noise amplifier (LNA) and a mixer and downconverts an RF input at 24GHz to an IF of 5 GHz. It has a power gain of 27.5 dB and an overall noise figure of 7.7 dB with an input return loss, S[sub]11 of 21 dB consuming 20 mA from a 1.5-V supply. The LNA achieves a power gain of 15 dB and a noise figure of 6 dB on 16 mA of dc current. The LNA's input stage utilizes a common-gate with resistive feedthrough topology. The performance analysis of this topology predicts the experimental results with good accuracy.", "doi": "10.1109/JSSC.2003.821783", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2004-02-01", "series_number": "2", "volume": "39", "issue": "2", "pages": "368-373" }, { "id": "authors:2s3fh-p3t51", "collection": "authors", "collection_id": "2s3fh-p3t51", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:WUHieeejssc03", "type": "article", "title": "Integrated Transversal Equalizers in High-Speed Fiber-Optic Systems", "author": [ { "family_name": "Wu", "given_name": "Hui", "clpid": "Wu-H" }, { "family_name": "Tierno", "given_name": "Jose A.", "clpid": "Tierno-J-A" }, { "family_name": "Pepeljugoski", "given_name": "Petar", "clpid": "Pepeljugoski-P" }, { "family_name": "Schaub", "given_name": "Jeremy", "clpid": "Schaub-J" }, { "family_name": "Gowda", "given_name": "Sudhir", "clpid": "Gowda-S" }, { "family_name": "Kash", "given_name": "Jeffrey A.", "clpid": "Kash-J-A" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Intersymbol interference (ISI) caused by intermodal dispersion in multimode fibers is the major limiting factor in the achievable data rate or transmission distance in high-speed multimode fiber-optic links for local area networks applications. Compared with optical-domain and other electrical-domain dispersion compensation methods, equalization with transversal filters based on distributed circuit techniques presents a cost-effective and low-power solution. The design of integrated distributed transversal equalizers is described in detail with focus on delay lines and gain stages. This seven-tap distributed transversal equalizer prototype has been implemented in a commercial 0.18-\u00b5m SiGe BiCMOS process for 10-Gb/s multimode fiber-optic links. A seven-tap distributed transversal equalizer reduces the ISI of a 10-Gb/s signal after 800 m of 50-\u00b5m multimode fiber from 5 to 1.38 dB, and improves the bit-error rate from about 10^-5 to less than 10^-12.", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2003-12-01", "series_number": "12", "volume": "38", "issue": "12", "pages": "2131-2137" }, { "id": "authors:ew4mh-9x724", "collection": "authors", "collection_id": "ew4mh-9x724", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:KEEieeetmtt03", "type": "article", "title": "The Class-E/F Family of ZVS Switching Amplifiers", "author": [ { "family_name": "Kee", "given_name": "Scott D.", "clpid": "Kee-S-D" }, { "family_name": "Aoki", "given_name": "Ichiro", "clpid": "Aoki-I" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Rutledge", "given_name": "David", "clpid": "Rutledge-D-B" } ], "abstract": "A new family of switching amplifiers, each member having some of the features of both class E and inverse F, is introduced. These class-E/F amplifiers have class-E features such as incorporation of the transistor parasitic capacitance into the circuit, exact truly switching time-domain solutions, and allowance for zero-voltage-switching operation. Additionally, some number of harmonics may be tuned in the fashion of inverse class F in order to achieve more desirable voltage and current waveforms for improved performance. Operational waveforms for several implementations are presented, and efficiency estimates are compared to class-E.", "doi": "10.1109/TMTT.2003.812564", "issn": "0018-9480", "publisher": "IEEE Transactions on Microwave Theory and Techniques", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2003-06-01", "series_number": "6", "volume": "51", "issue": "6", "pages": "1677-1690" }, { "id": "authors:haq0x-nke82", "collection": "authors", "collection_id": "haq0x-nke82", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HAMieeejssc03", "type": "article", "title": "Virtual damping and Einstein relation in oscillators", "author": [ { "family_name": "Ham", "given_name": "Donhee", "clpid": "Ham-D" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "This paper presents a new physical theory of oscillator phase noise. Built around the concept of phase diffusion, this work bridges the fundamental physics of noise and existing oscillator phase-noise theories. The virtual damping of an ensemble of oscillators is introduced as a measure of phase noise. The explanation of linewidth compression through virtual damping provides a unified view of resonators and oscillators. The direct correspondence between phase noise and the Einstein relation is demonstrated, which reveals the underlying physics of phase noise. The validity of the new approach is confirmed by consistent experimental agreement.", "doi": "10.1109/JSSC.2002.808283", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2003-03", "series_number": "3", "volume": "38", "issue": "3", "pages": "407-418" }, { "id": "authors:g6ykc-20t19", "collection": "authors", "collection_id": "g6ykc-20t19", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:APAieeejssc02b", "type": "article", "title": "A Noise-Shifting Differential Colpitts VCO", "author": [ { "family_name": "Aparicio", "given_name": "Roberto", "clpid": "Aparicio-R" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "A novel noise-shifting differential Colpitts VCO is presented. It uses current switching to lower phase noise by cyclostationary noise alignment and improve the start-up condition. A design strategy is also devised to enhance the phase noise performance of quadrature coupled oscillators. Two integrated VCOs are presented as design examples.", "doi": "10.1109/JSSC.2002.804354", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2002-12-01", "series_number": "12", "volume": "37", "issue": "12", "pages": "1728-1736" }, { "id": "authors:b2gde-f7w23", "collection": "authors", "collection_id": "b2gde-f7w23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:WHIel02", "type": "article", "title": "Phase noise in distributed oscillators", "author": [ { "family_name": "White", "given_name": "C. J.", "clpid": "White-C-J" }, { "family_name": "Hajimiri", "given_name": "A.", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "The phase noise of a distributed oscillator is evaluated very simply by identifying an effective capacitance equal to the total capacitance distributed along the transmission lines. The contributions of the various passive and active noise sources to the total phase noise are calculated revealing several guidelines for improved distributed oscillator designs.", "doi": "10.1049/el:20020982", "issn": "0013-5194", "publisher": "Electronics Letters", "publication": "Electronics Letters", "publication_date": "2002-11-07", "series_number": "23", "volume": "38", "issue": "23", "pages": "1453-1454" }, { "id": "authors:56ebc-6qa97", "collection": "authors", "collection_id": "56ebc-6qa97", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:APAieeejssc02a", "type": "article", "title": "Capacity limits and matching properties of integrated capacitors", "author": [ { "family_name": "Aparicio", "given_name": "Roberto", "clpid": "Aparicio-R" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Theoretical 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 quasifractal 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.", "doi": "10.1109/4.987091", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2002-03-01", "series_number": "3", "volume": "37", "issue": "3", "pages": "384-393" }, { "id": "authors:rtpz5-41f87", "collection": "authors", "collection_id": "rtpz5-41f87", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:AOKieeejssc02", "type": "article", "title": "Fully integrated CMOS power amplifier design using the distributed active-transformer architecture", "author": [ { "family_name": "Aoki", "given_name": "Ichiro", "clpid": "Aoki-I" }, { "family_name": "Kee", "given_name": "Scott D.", "clpid": "Kee-S-D" }, { "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" } ], "abstract": "A novel on-chip impedance matching and power-combining method, the distributed active transformer is presented. It combines several low-voltage push-pull amplifiers efficiently with their outputs in series 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 reproducible. To demonstrate the feasibility of this concept, a 2.4-GHz 2-W 2-V truly fully integrated power amplifier with 50-\u03a9 input and output matching has been fabricated using 0.35-\u03bcm CMOS transistors. It achieves a power added efficiency (PAE) of 41 % at this power level. It can also produce 450 mW using a 1-V supply. Harmonic suppression is 64 dBc or better. This new topology makes possible a truly fully integrated watt-level gigahertz range low-voltage CMOS power amplifier for the first time.", "doi": "10.1109/4.987090", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2002-03-01", "series_number": "3", "volume": "37", "issue": "3", "pages": "371-383" }, { "id": "authors:8pct1-fwy06", "collection": "authors", "collection_id": "8pct1-fwy06", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HAJieeecm02", "type": "article", "title": "Distributed Integrated Circuits: An Alternative Approach to High-Frequency Design", "author": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Distributed integrated circuits are presented as a methodology to design high-frequency communication building blocks. Distributed circuits operate based on multiple parallel signal paths working in synchronization that can be used to enhance the frequency of operation, combine power, and enhance the robustness of the design. These multiple signal paths usually result in strong couplings inside the circuit that necessitate\na treatment spanning architecture, circuits, devices, and electromagnetic levels of abstraction.", "doi": "10.1109/35.983925", "issn": "0163-6804", "publisher": "IEEE Communications Magazine", "publication": "IEEE Communications Magazine", "publication_date": "2002-02-01", "series_number": "2", "volume": "40", "issue": "2", "pages": "168-173" }, { "id": "authors:9b0pp-sp920", "collection": "authors", "collection_id": "9b0pp-sp920", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:AOKieeemtt02", "type": "article", "title": "Distributed active transformer - a new power-combining andimpedance-transformation technique", "author": [ { "family_name": "Aoki", "given_name": "Ichiro", "clpid": "Aoki-I" }, { "family_name": "Kee", "given_name": "Scott D.", "clpid": "Kee-S-D" }, { "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" } ], "abstract": "In this paper, we compare the performance of the newly introduced distributed active transformer (DAT) structure to that of conventional on-chip impedance-transformations methods. Their fundamental power-efficiency limitations in the design of high-power fully integrated amplifiers in standard silicon process technologies are analyzed. The DAT is demonstrated to be an efficient impedance-transformation and power-combining method, which combines several low-voltage push-pull amplifiers in series by magnetic coupling. To demonstrate the validity of the new concept, a 2.4-GHz 1.9-W 2-V fully integrated power-amplifier achieving a power-added efficiency of 41% with 50-\u03a9 input and output matching has been fabricated using 0.35-\u03bcm CMOS transistors", "doi": "10.1109/22.981284", "issn": "0018-9480", "publisher": "IEEE Transactions on Microwave Theory and Techniques", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2002-01-01", "series_number": "1, pt.", "volume": "50", "issue": "1, pt.", "pages": "316-331" }, { "id": "authors:p6zms-zhr15", "collection": "authors", "collection_id": "p6zms-zhr15", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HASieeetmtt02", "type": "article", "title": "Concurrent multiband low-noise amplifiers -- theory, design, and applications", "author": [ { "family_name": "Hashemi", "given_name": "Hossein", "clpid": "Hashemi-H" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "The concept of concurrent multiband low-noise-amplifiers (LNAs) is introduced. A systematic way to design concurrent multiband integrated LNAs in general is developed. Applications of concurrent multiband LNAs in concurrent multiband receivers together with receiver architecture are discussed. Experimental results of a dual-band LNA implemented in a 0.35-\u03bcm CMOS technology as a demonstration of the concept and theory is presented.", "doi": "10.1109/22.981282", "issn": "0018-9480", "publisher": "IEEE Transactions on Microwave Theory and Techniques", "publication": "IEEE Transactions on Microwave Theory and Techniques", "publication_date": "2002-01-01", "series_number": "1", "volume": "50", "issue": "1", "pages": "288-301" }, { "id": "authors:8tyjy-3p546", "collection": "authors", "collection_id": "8tyjy-3p546", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HAMieeejssc01", "type": "article", "title": "Concepts and methods in optimization of integrated LC VCOs", "author": [ { "family_name": "Ham", "given_name": "Donhee", "clpid": "Ham-D" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Underlying physical mechanisms controlling the noise properties of oscillators are studied. This treatment shows the importance of inductance selection for oscillator noise optimization. A design strategy centered around an inductance selection scheme is executed using a practical graphical optimization method to optimize phase noise subject to design constraints such as power dissipation, tank amplitude, tuning range, startup condition, and diameters of spiral inductors. The optimization technique is demonstrated through a design example, leading to a 2.4-GHz fully integrated, LC voltage-controlled oscillator (VCO) implemented using 0.35-\u03bcm MOS transistors. The measured phase-noise values are -121, -117, and -115 dBc/Hz at 600-kHz offset from 1.91, 2.03, and 2.60-GHz carriers, respectively. The VCO dissipates 4 mA from a 2.5-V supply voltage. The inversion mode MOSCAP tuning is used to achieve 26% of tuning range. Two figures of merit for performance comparison of various oscillators are introduced and used to compare this work to previously reported results.", "doi": "10.1109/4.924852", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2001-06", "series_number": "6", "volume": "36", "issue": "6", "pages": "896-909" }, { "id": "authors:9cbmc-jj058", "collection": "authors", "collection_id": "9cbmc-jj058", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:WUHieeejssc01", "type": "article", "title": "Silicon-based distributed voltage-controlled oscillators", "author": [ { "family_name": "Wu", "given_name": "Hui", "clpid": "Wu-H" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Distributed voltage-controlled oscillators (DVCOs) are presented as a new approach to the design of silicon VCOs at microwave frequencies. In this paper, the operation of distributed oscillators is analyzed and the general oscillation condition is derived, resulting in analytical expressions for the frequency and amplitude. Two tuning techniques for DVCOs are demonstrated, namely, the inherent-varactor tuning and delay-balanced current-steering tuning. A complete analysis of the tuning techniques is presented. CMOS and bipolar DVCOs have been designed and fabricated in a 0.35-\u03bcm BiCMOS process. A 10-GHz CMOS DVCO achieves a tuning range of 12% (9.3-10.5 GHz) and a phase noise of -103 dBc/Hz at 600 kHz offset from the carrier. The oscillator provides an output power of -4.5 dBm without any buffering, drawing 14 mA of dc current from a 2.5-V power supply. A 12-GHz bipolar DVCO consuming 6 mA from a 2.5-V power supply is also demonstrated. It has a tuning range of 26% with a phase noise of -99 dBc/Hz at 600 kHz offset from the carrier.", "doi": "10.1109/4.910488", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2001-03-01", "series_number": "3", "volume": "36", "issue": "3", "pages": "493-502" }, { "id": "authors:rx96f-mzt47", "collection": "authors", "collection_id": "rx96f-mzt47", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:LEEieeejssc00", "type": "article", "title": "Oscillator phase noise: a tutorial", "author": [ { "family_name": "Lee", "given_name": "Thomas H.", "clpid": "Lee-T-H" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" } ], "abstract": "Linear time-invariant (LTI) phase noise theories provide important qualitative design insights but are limited in their quantitative predictive power. Part of the difficulty is that device noise undergoes multiple frequency translations to become oscillator phase noise. A quantitative understanding of this process requires abandoning the principle of time invariance assumed in most older theories of phase noise. Fortunately, the noise-to-phase transfer function of oscillators is still linear, despite the existence of the nonlinearities necessary for amplitude stabilization. In addition to providing a quantitative reconciliation between theory and measurement, the time-varying phase noise model presented in this tutorial identifies the importance of symmetry in suppressing the upconversion of 1/f noise into close-in phase noise, and provides an explicit appreciation of cyclostationary effects and AM-PM conversion. These insights allow a reinterpretation of why the Colpitts oscillator exhibits good performance, and suggest new oscillator topologies. Tuned LC and ring oscillator circuit examples are presented to reinforce the theoretical considerations developed. Simulation issues and the accommodation of amplitude noise are considered in appendixes.", "doi": "10.1109/4.826814", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2000-03-01", "series_number": "3", "volume": "35", "issue": "3", "pages": "326-336" }, { "id": "authors:a6xyn-rjd88", "collection": "authors", "collection_id": "a6xyn-rjd88", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20111212-151657259", "type": "article", "title": "Comments on \"Design issues in CMOS differential LC oscillators\" [and reply]", "author": [ { "family_name": "Wang", "given_name": "HongMo", "clpid": "Wang-H-M" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Lee", "given_name": "Thomas H.", "clpid": "Lee-T-H" } ], "abstract": "For the original paper see ibid., vol. 34, no. 5, p. 717-24 (1999). The commenter points out that the phase noise difference reported in the aforementioned paper appears to have a topological cause, and he presents a simple analysis to show that the difference is 6 dB under otherwise identical conditions. In reply, the authors clarify some points in their original work.", "doi": "10.1109/4.823455", "issn": "0018-9200", "publisher": "IEEE", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "2000-02", "series_number": "2", "volume": "35", "issue": "2", "pages": "286-287" }, { "id": "authors:1hw2y-5p770", "collection": "authors", "collection_id": "1hw2y-5p770", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HAJieeejssc99a", "type": "article", "title": "Jitter and phase noise in ring oscillators", "author": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Limotyrakis", "given_name": "Sotirios", "clpid": "Limotyrakis-S" }, { "family_name": "Lee", "given_name": "Thomas H.", "clpid": "Lee-T-H" } ], "abstract": "A companion analysis of clock jitter and phase noise of single-ended and differential ring oscillators is presented. The impulse sensitivity functions are used to derive expressions for the jitter and phase noise of ring oscillators. The effect of the number of stages, power dissipation, frequency of oscillation, and short-channel effects on the jitter and phase noise of ring oscillators is analyzed. Jitter and phase noise due to substrate and supply noise is discussed, and the effect of symmetry on the upconversion of 1/f noise is demonstrated. Several new design insights are given for low jitter/phase-noise design. Good agreement between theory and measurements is observed.", "doi": "10.1109/4.766813", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "1999-06-01", "series_number": "6", "volume": "34", "issue": "6", "pages": "790-804" }, { "id": "authors:cx5j0-4p583", "collection": "authors", "collection_id": "cx5j0-4p583", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HAJieeejssc99b", "type": "article", "title": "Design issues in CMOS differential LC oscillators", "author": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Lee", "given_name": "Thomas H.", "clpid": "Lee-T-H" } ], "abstract": "An analysis of phase noise in differential cross-coupled inductance-capacitance (LC) oscillators is presented. The effect of tail current and tank power dissipation on the voltage amplitude is shown. Various noise sources in the complementary cross-coupled pair are identified, and their effect on phase noise is analyzed. The predictions are in good agreement with measurements over a large range of tail currents and supply voltages. A 1.8 GHz LC oscillator with a phase noise of -121 dBc/Hz at 600 kHz is demonstrated, dissipating 6 mW of power using on-chip spiral inductors.", "doi": "10.1109/4.760384", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "1999-05-01", "series_number": "5", "volume": "34", "issue": "5", "pages": "717-724" }, { "id": "authors:8f4yr-hza08", "collection": "authors", "collection_id": "8f4yr-hza08", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:SAMieeejssc98", "type": "article", "title": "Fractal capacitors", "author": [ { "family_name": "Samavati", "given_name": "Hirad", "clpid": "Samavati-H" }, { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Shahani", "given_name": "Arvin R.", "clpid": "Shahani-A-R" }, { "family_name": "Nasserbakht", "given_name": "Gitty N.", "clpid": "Nasserbakht-G-N" }, { "family_name": "Lee", "given_name": "Thomas H.", "clpid": "Lee-T-H" } ], "abstract": "A linear capacitor structure using fractal geometries is described. This capacitor exploits both lateral and vertical electric fields to increase the capacitance per unit area. Compared to standard parallel-plate capacitors, the parasitic bottom-plate capacitance is reduced. Unlike conventional metal-to-metal capacitors, the capacitance density increases with technology scaling. A classic fractal structure is implemented with 0.6-\u03bcm metal spacing, and a factor of 2.3 increase in the capacitance per unit area is observed. It is shown that capacitance boost factors in excess of ten may be possible as technology continues to scale. A computer-aided-design tool to automatically generate and analyze custom fractal layouts has been developed.", "doi": "10.1109/4.735545", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "1998-12-01", "series_number": "12", "volume": "33", "issue": "12", "pages": "2035-2041" }, { "id": "authors:r11pe-dnn76", "collection": "authors", "collection_id": "r11pe-dnn76", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:HAJieeejssc98", "type": "article", "title": "A general theory of phase noise in electrical oscillators", "author": [ { "family_name": "Hajimiri", "given_name": "Ali", "orcid": "0000-0001-6736-8019", "clpid": "Hajimiri-A" }, { "family_name": "Lee", "given_name": "Thomas H.", "clpid": "Lee-T-H" } ], "abstract": "A general model is introduced which is capable of making accurate, quantitative predictions about the phase noise of different types of electrical oscillators by acknowledging the true periodically time-varying nature of all oscillators. This new approach also elucidates several previously unknown design criteria for reducing close-in phase noise by identifying the mechanisms by which intrinsic device noise and external noise sources contribute to the total phase noise. In particular, it explains the details of how 1/f noise in a device upconverts into close-in phase noise and identifies methods to suppress this upconversion. The theory also naturally accommodates cyclostationary noise sources, leading to additional important design insights. The model reduces to previously available phase noise models as special cases. Excellent agreement among theory, simulations, and measurements is observed.", "doi": "10.1109/4.658619", "issn": "0018-9200", "publisher": "IEEE Journal of Solid-State Circuits", "publication": "IEEE Journal of Solid-State Circuits", "publication_date": "1998-02", "series_number": "2", "volume": "33", "issue": "2", "pages": "179-194" } ]