CaltechAUTHORS: Monograph
https://feeds.library.caltech.edu/people/Mead-C-A/monograph.rss
A Caltech Library Repository Feedhttp://www.rssboard.org/rss-specificationpython-feedgenenMon, 14 Oct 2024 07:28:59 -0700Basic Limitations in Microcircuit Fabrication Technology
https://resolver.caltech.edu/CaltechAUTHORS:20150927-232217795
Year: 1976
This report presents the findings of a 6-month study undertaken for the Defense Advanced Research Projects Agency to ascertain what, if any, research ARPA might sensibly conduct in integrated microcircuit technology. The authors entered upon the study through a conviction that serious international competition in this technology may appear in the next few years, and a desire to ensure for the United States as favorable an opportunity to meet this competition as research can make available. Both the ubiquitous nature of micro-electronics in defense applications and the particularly severe special defense requirements for complex, low-power, micro-miniaturized circuitry make a commanding lead in this technology very important. The authors wished to assure themselves and ARPA that the existing research programs provide adequately for the forthcoming needs of the nation. The report details some high-leverage research areas, not now receiving government or private support, where relatively small, advanced research efforts may have substantial payoff. No endorsement of the study conclusions by ARPA is implied or intended.https://resolver.caltech.edu/CaltechAUTHORS:20150927-232217795Minimum Propagation Delays in VLSI
https://resolver.caltech.edu/CaltechAUTHORS:20120423-103239364
Year: 1982
DOI: 10.7907/7w91m-s9v80
Conditions are outlined under which propagation delays in
VLSI circuits can be achieved that are logarithmic in the wire lengths. These conditions are imposed by area requirements and the velocity of light.https://resolver.caltech.edu/CaltechAUTHORS:20120423-103239364Formal Specification of Concurrent Systems
https://resolver.caltech.edu/CaltechCSTR:1982-5042-tr-82
Year: 1982
DOI: 10.7907/kmq8e-ezn08
No Abstract.https://resolver.caltech.edu/CaltechCSTR:1982-5042-tr-82A Hierarchical Simulator Based on Formal Semantics
https://resolver.caltech.edu/CaltechAUTHORS:20120420-111744031
Year: 1983
DOI: 10.7907/jz6sz-1pt23
N/Ahttps://resolver.caltech.edu/CaltechAUTHORS:20120420-111744031Signal Delay in General RC Networks with Application to Timing Simulation of Digital Integrated Circuits
https://resolver.caltech.edu/CaltechCSTR:1983.5089-tr-83
Year: 1983
DOI: 10.7907/h46fc-bcr96
Modeling digital MOS circuits by RC networks has become a well accepted practice for estimating delays. In 1981, Penfield and Rubinstein proposed a method to bound the
delays of the nodes in an RC tree network. In this paper, we address the problem of dynamic timing simulation under RC-based models. Based upon the delay of Elmore, a
single value of delay is derived for any node in a general RC network. The effects of parallel
connections and stored charges are properly taken into consideration. The algorithm can
be used either as a stand-alone simulator, or as a front end for producing initial waveforms
for waveform-relaxation based circuit simulators. An experimental simulator called SDS
(Signal Delay Simulator) has been developed. For all the examples tested so far, this
simulator runs about two to three orders of magnitude faster than SPICE, and detects all
transitions and glitches at approximately the correct time.https://resolver.caltech.edu/CaltechCSTR:1983.5089-tr-83Minimum propagation delays in VLSI
https://resolver.caltech.edu/CaltechAUTHORS:20120420-104637505
Year: 1983
DOI: 10.7907/xzm6p-fzr13
In this paper we demonstrate that it is possible to achieve propagation delays that are logarithmic in the lengths of the wires, provided the connection pattern is designed to meet rather strong constraints. These constraints are, in
effect, satisfied only by connection patterns that exhibit a hierarchical structure. We also show that, even at the ultimate physical limits of the technology, the
propagation for reasonably sized VLSI chips is dominated by these considerations, rather than by the speed of light.https://resolver.caltech.edu/CaltechAUTHORS:20120420-104637505A VLSI Architecture for Sound Synthesis
https://resolver.caltech.edu/CaltechCSTR:1984.5158-tr-84
Year: 1984
DOI: 10.7907/3d575-yvm11
No Abstract.https://resolver.caltech.edu/CaltechCSTR:1984.5158-tr-84The Wolery
https://resolver.caltech.edu/CaltechCSTR:1984.5113-tr-84
Year: 1984
DOI: 10.7907/43z52-rx643
No Abstract.https://resolver.caltech.edu/CaltechCSTR:1984.5113-tr-84An electronic model of the y-system of mammalian retina
https://resolver.caltech.edu/CaltechAUTHORS:20220523-171311035
Year: 1984
<p>A set of detailed circuits are described that implement what we believe to be a reasonably faithful model of the y-system of the retina. The model is shown in block-diagram form in Fig. 1. It consists of: 1. An array of receptors, R, such as those described in DF5121. 2. A resistive network with capacitance to ground, modeling the horizontal cells. The horizontal resistors, H, provide lateral conductance that can be loosely thought of as a model of the gap-junctions between cells. The cell capacitances are modeled as lumped elements. 3. Triad synapses, TS, that take the difference between the potential of the horizontal network and that receptor output, and drag the local potential of the horizontal network along in the process. 4. Bipolar cells, B, that threshold the output of the triad synapses and carry the signal forward. 5. Amacrine cells, A, that sum an asymmetric surround of bipolar outputs. 6. Receptive field units, RFU, that apply the amacrine inhibition to the bipolar outputs. 7. A dendritic network, DN, in which a number of receptive fields are summed. 8. The Ganglion cell proper, G, that integrates the DN sum with respect to time, and issues an output pulse if the integral exceeds some threshold.</p>https://resolver.caltech.edu/CaltechAUTHORS:20220523-171311035Winner-Take-All Networks of O(N) Complexity
https://resolver.caltech.edu/CaltechCSTR:1988.cs-tr-88-21
Year: 1988
DOI: 10.7907/32s8b-x9954
No abstract available.https://resolver.caltech.edu/CaltechCSTR:1988.cs-tr-88-21Cochlear Hydrodynamics Demystified
https://resolver.caltech.edu/CaltechCSTR:1988.cs-tr-88-04
Year: 1988
DOI: 10.7907/qysdt-52n82
Wave propagation in the mammalian cochlea (inner ear) is modeled as a unidirectional cascade of simple filters. The transfer functions of the low-order filter stages are completely determined by the wave-number vs. frequency solutions to the dispersion relations that describe the cochlea, which are in turn derived from twodimensional approximations to the fluid mechanics. Active undamping effects of the outer hair cells are easily included in the analysis and modeling, so that the results can be directly applied in the design of active adaptive cochlear models.https://resolver.caltech.edu/CaltechCSTR:1988.cs-tr-88-04Cost and Performance of VLSI Computing Structures
https://resolver.caltech.edu/CaltechCSTR:1978.1584-tr-78
Year: 2002
DOI: 10.7907/fm4yx-3bq89
Using VLSI technology, it will soon be possible to implement entire computing systems on one monolithic Silicon chip. What will the nature of such systems be? How will they be designed? What will be their cost and performance? Conducting paths are required for communicating information throughout any integrated system. The length and organization of these communication paths places a lower bound on the area and time required for system operations. Optimal designs can be achieved in only a few of the many alternative structures. Two illustrative systems are analyzed in detail: a RAM based system and an associative system. It is shown that in each case an optimum design is possible, using the area – time product as a cost function.https://resolver.caltech.edu/CaltechCSTR:1978.1584-tr-78A notation for designing restoring logic circuitry in CMOS
https://resolver.caltech.edu/CaltechCSTR:1981.4600-tr-81
Year: 2008
We introduce a programming notation in which every syntactically correct program specifies a restoring logic component, i.e., a component whose outputs are permanently connected, via "not too many" transistors, to the power supply. It is shown how the specified components can be translated into transistor diagrams for CMOS integrated circuits. As these components are designed as strict hierarchies, it is hoped that the translation of the transistor diagrams into layouts for integrated circuits can be accomplished mechanically.https://resolver.caltech.edu/CaltechCSTR:1981.4600-tr-81Optimum Noise Performance of Transistor Input Circuits / Transistor AC and DC Amplifiers with High Input Impedance
https://resolver.caltech.edu/CaltechAUTHORS:20121108-143232418
Year: 2012
Some results are presented for optimum noise performance of transistor input stages when fed from resistive or reactive sources. Standard theory has shown that a common-emitter transistor fed from a resistive source presents a minimum noise figure F_m when the source resistance has a certain value R_gm in the order of lkΩ. In this
paper, expressions are developed for minimum noise figure and optimum
source resistance in the presence of base bias resistors, emitter degeneration
resistance, and various kinds of feedback. Results are in
terms of F_m and R_gm only, and do not contain other functions of the
transistor internal noise sources. It is shown that the minimum noise
figure is never less than F_m, but the optimum source resistance can be
either greater or less than R_gm.
In the case of reactive sources, noise figure is meaningless and
the quantity of interest is signal-to-noise ratio over the passband.
It is shown that for an inductive source, such as a magnetic tape head,
there is a maximum signal-to-noise ratio obtainable with an optimum
source inductance, and that a Figure of Merit can be assigned to the
source which is independent of its inductance.
Experimental results presented for both resistive and inductive
sources show good agreement with the theoretical predictions.https://resolver.caltech.edu/CaltechAUTHORS:20121108-143232418Gravitational Waves in G4v
https://resolver.caltech.edu/CaltechAUTHORS:20150819-134952067
Year: 2015
DOI: 10.48550/arXiv.1503.04866
Gravitational coupling of the propagation four-vectors of matter wave functions is formulated in at space-time. Coupling at the momentum level rather than at the "force-law" level greatly simplifies many calculations. This locally Lorentz-invariant approach (G4v) treats electromagnetic and gravitational coupling on an equal footing. Classical mechanics emerges from the incoherent aggregation of matter wave functions. The theory reproduces, to first order beyond Newton, the
standard GR results for Gravity-Probe B, deflection of light by massive bodies, precession of orbits, gravitational red shift, and total gravitational-wave energy radiated by a circular binary system. Its predictions differ markedly from GR for the gravitational-wave radiation patterns from rotating massive systems, and for the LIGO antenna pattern. G4v predictions of total radiated energy from highly eccentric Kepler systems are slightly larger than those of similar GR treatments. A detailed treatment of the theory is in preparation. However the generation and detection of gravitational waves is exactly the same as the corresponding treatment for electromagnetic waves given in
Collective Electrodynamics, (hereinafter referred to simply as CE) and therefore separable from the material in preparation. It therefore seems advisable to make the gravitational-wave material available, since
its predictions should be testable as data from Advanced LIGO becomes available over the next few years. The presentation is somewhat more detailed than would be "normal," simply to make the approach clear and accessible to non-specialists.https://resolver.caltech.edu/CaltechAUTHORS:20150819-134952067Refractory Neuron Circuits
https://resolver.caltech.edu/CaltechAUTHORS:20150908-164345500
Year: 2015
Neural networks typically use an abstraction of the behaviour of a biological neuron, in which
the continuously varying mean firing rate of the neuron is presumed to carry information about
the neuron's time-varying state of excitation. However, the detailed timing of action potentials is
known to be important in many biological systems. To build electronic models of such systems,
one must have well-characterized neuron circuits that capture the essential behaviour of real
neurons in biological systems. In this paper, we describe two simple and compact circuits that
fire narrow action potentials with controllable thresholds, pulse widths, and refractory periods.
Both circuits are well suited as high-level abstractions of spiking neurons. We have used the first
circuit to generate action potentials from a current input, and have used the second circuit to
delay and propagate action potentials in an axon delay line. The circuit mechanisms are derived
from the behaviour of sodium and potassium conductances in nerve membranes of biological
neurons. The first circuit models behaviours at the axon hillock; the second circuit models
behaviour at the node of Ranvier in biological neurons. The circuits have been implemented in
a 2-micron double-poly CMOS process. Results are presented from working chips.https://resolver.caltech.edu/CaltechAUTHORS:20150908-164345500Analog VLSI Phototransduction by continuous-time, adaptive, logarithmic photoreceptor circuits
https://resolver.caltech.edu/CaltechAUTHORS:20150908-164952926
Year: 2015
Over the last few years, we and others have built a number of interesting neuromorphic analog vision chips that do focal-plane time-domain computation. These chips do local, continuous-time, spatiotemporal processing that takes place before any sampling or long-range communication, for example, motion processing, change detection, neuromorphic retinal preprocessing, stereo image matching, and synthesis of auditory images from visual scenes.
This processing requires photoreceptor
circuits that transduce from light falling on
the chip to an electrical signal. If we want
to build analog vision chips that do high-quality
focal plane processing, then we
need good photoreceptors. It's not enough
to just demonstrate a concept; ultimate usefulness
will be determined by market forces,
which, among other factors, depend a
lot on raw performance. The receptor circuits
we discuss here have not been used in
any commercial product, so they have not
yet passed that most crucial test, but by every
performance metric we can come up
with, including successful fabrication and
test of demonstration systems, they match
performance criteria met by other phototransduction
techniques that are used in
end-product consumer electronic devices.
We hope that this article will serve several
purposes: We want people to have a reference
where they can look to see the
functioning and practical problems of phototransducers
built in a typical CMOS or
BiCMOS process. We want to inspire people
to build low-power, integrated commercial
vision devices for practical
purposes. We want to provide a photoreceptor
that can be used as a front end transducer
in more advanced research on
neuromorphic systems.
The transduction process seems mundane,
but it is important --GIGO comes to
mind. Subsequent computation relies on the
information. We don't know of any contemporary
(VLSI-era) literature that comprehensively
explore the subject. Previous
results are lacking in some aspect, either in
the circuit itself, or in the understanding of
the physics, or in the realistic measurement
of limitations on behavior.
We'll focus on one highly-evolved adaptive
receptor circuit to understand how it
operates, what are the limitations on its dynamic
range, and what is the physics of the
noise behavior. The receptor has new and
previously unpublished technical improvements,
and we understand the noise properties
and illumination limits much better
than we did before. We'll also discuss the
practical aspects of the interaction of light
with silicon: What are the spectral responses
of various devices? How far do light-generated
minority carriers diffuse and how
do they affect circuit operation? How effective
are guard bars to protect against them?
Finally, we'll talk about biological receptors:
How do their functional characteristics
inspire the electronic model? How are the
mechanisms of gain and adaptation related?https://resolver.caltech.edu/CaltechAUTHORS:20150908-164952926Optical Flow and Surface Interpolation in Resistive Networks: Algorithms and Analog VLSI Chips
https://resolver.caltech.edu/CaltechAUTHORS:20151029-101037556
Year: 2015
To us, and to other biological organisms, vision seems effortless. We open our eyes and we "see" the world in all its color, brightness, and movement. Flies, frogs, cats, and humans can all equally well perceive a rapidly changing environment and act on it. Yet, we have great difficulties when trying to endow our machines with similar abilities. In this article, we describe
recent developments in the theory of early vision that led from the formulation of the motion problem as an ill-posed one to its solution by minimizing certain "cost" functions. These cost or energy functions can be mapped onto simple analog and digital resistive networks. For instance, as
detailed in this chapter, we can compute the optical flow by injecting currents into resistive networks and recording the resulting stationary voltage distribution at each node. These networks, which are implemented in subthreshold, analog, complementary metal oxide semiconductor (CMOS) very
large scale integrated (VLSI) circuits, are very attractive for their technological potential.https://resolver.caltech.edu/CaltechAUTHORS:20151029-101037556Potential Major Improvement in Superconductors for High-Field Magnets
https://resolver.caltech.edu/CaltechAUTHORS:20230414-212445417
Year: 2023
DOI: 10.48550/arXiv.2304.06171
Fusion reactors are limited by the magnetic field available to confine their plasma. The commercial fusion industry uses the larger magnetic field and higher operating temperature of the cuprate superconductor YBa₂Cu₃O_(7−δ) (YBCO) in order to confine their plasma into a dense volume. A superconductor is a macroscopic quantum state that is protected from the metallic (resistive) state by an energy gap. Unfortunately, YBCO has an anisotropic gap, known as D-wave because it has the shape of a d_(x²−y²) chemical orbital. This D-wave gap means that poly-crystalline wire cannot be made because a few degree misalignment between grains in the wire leads to a drastic loss in its supercurrent carrying ability, and thereby its magnetic field limit. The superconductor industry has responded by growing nearly-single-crystal superconducting YBCO films on carefully prepared substrate tapes kilometers in length. Heroic development programs have made such tapes commercially available, but they are very expensive and delicate. MRI magnet superconductors, such as NbTi and Nb3Sn, are formed into poly-crystalline wires because they have an isotropic gap in the shape of an s chemical orbital (called S-wave) that makes them insensitive to grain misalignment. However, these materials are limited to lower magnetic fields and liquid-He temperatures. Here, we modified YBCO by doping the Y site with Ca and Ce atoms to form (Y₁₋ₓ₋ᵧCaₓCeᵧ)Ba₂Cu₃O_(7−δ), and show evidence that it changes to an S-wave gap. Its superconducting transition temperature, T꜀, of ∼70K, while lower than that of D-wave YBCO at ∼90K, is easily maintained using common, economic cryogenic equipment.https://resolver.caltech.edu/CaltechAUTHORS:20230414-212445417Propagation of pulsed light in an optical cavity in a gravitational field
https://authors.library.caltech.edu/records/rtkg1-zce31
Year: 2024
DOI: 10.48550/arXiv.2408.03384
<p>All modern theories of gravitation, starting with Newton's, predict that gravity will affect the speed of light propagation. Einstein's theory of General Relativity famously predicted that the effect is twice the Newtonian value, a prediction that was verified during the 1919 solar eclipse. Recent theories of vector gravity can be interpreted to imply that gravity will have a different effect on pulsed light versus continuous-wave (CW) light propagating between the two mirrors of an optical cavity. Interestingly, we are not aware of any previous experiments to determine the relative effect of gravity on the propagation of pulsed versus CW light. In order to observe if there are small differences, we use a 6 GHz electro-optic frequency comb and low-noise CW laser to make careful measurements of the resonance frequencies of a high-finesse optical cavity. Once correcting for the effects of mirror dispersion, we determine that the cavity resonance frequencies for pulsed and CW light are the same to within our experimental error, which is on the order of 10⁻<span class="legacy-color-text-default">¹</span><span class="legacy-color-text-default">² </span><span class="MathJax"><span class="math"><span class="mrow"><span class="msubsup"><span class="texatom"><span class="mrow"><span class="mn">of the optical frequency, and one part in 700 of the expected gravitational shift.</span></span></span></span></span></span></span></p>https://authors.library.caltech.edu/records/rtkg1-zce31