10,623 research outputs found
PieceTimer: A Holistic Timing Analysis Framework Considering Setup/Hold Time Interdependency Using A Piecewise Model
In static timing analysis, clock-to-q delays of flip-flops are considered as
constants. Setup times and hold times are characterized separately and also
used as constants. The characterized delays, setup times and hold times, are
ap- plied in timing analysis independently to verify the perfor- mance of
circuits. In reality, however, clock-to-q delays of flip-flops depend on both
setup and hold times. Instead of being constants, these delays change with
respect to different setup/hold time combinations. Consequently, the simple ab-
straction of setup/hold times and constant clock-to-q delays introduces
inaccuracy in timing analysis. In this paper, we propose a holistic method to
consider the relation between clock-to-q delays and setup/hold time
combinations with a piecewise linear model. The result is more accurate than
that of traditional timing analysis, and the incorporation of the
interdependency between clock-to-q delays, setup times and hold times may also
improve circuit performance.Comment: IEEE/ACM International Conference on Computer-Aided Design (ICCAD),
November 201
Discrete-Time Chaotic-Map Truly Random Number Generators: Design, Implementation, and Variability Analysis of the Zigzag Map
In this paper, we introduce a novel discrete chaotic map named zigzag map
that demonstrates excellent chaotic behaviors and can be utilized in Truly
Random Number Generators (TRNGs). We comprehensively investigate the map and
explore its critical chaotic characteristics and parameters. We further present
two circuit implementations for the zigzag map based on the switched current
technique as well as the current-mode affine interpolation of the breakpoints.
In practice, implementation variations can deteriorate the quality of the
output sequence as a result of variation of the chaotic map parameters. In
order to quantify the impact of variations on the map performance, we model the
variations using a combination of theoretical analysis and Monte-Carlo
simulations on the circuits. We demonstrate that even in the presence of the
map variations, a TRNG based on the zigzag map passes all of the NIST 800-22
statistical randomness tests using simple post processing of the output data.Comment: To appear in Analog Integrated Circuits and Signal Processing (ALOG
Calculation of Generalized Polynomial-Chaos Basis Functions and Gauss Quadrature Rules in Hierarchical Uncertainty Quantification
Stochastic spectral methods are efficient techniques for uncertainty
quantification. Recently they have shown excellent performance in the
statistical analysis of integrated circuits. In stochastic spectral methods,
one needs to determine a set of orthonormal polynomials and a proper numerical
quadrature rule. The former are used as the basis functions in a generalized
polynomial chaos expansion. The latter is used to compute the integrals
involved in stochastic spectral methods. Obtaining such information requires
knowing the density function of the random input {\it a-priori}. However,
individual system components are often described by surrogate models rather
than density functions. In order to apply stochastic spectral methods in
hierarchical uncertainty quantification, we first propose to construct
physically consistent closed-form density functions by two monotone
interpolation schemes. Then, by exploiting the special forms of the obtained
density functions, we determine the generalized polynomial-chaos basis
functions and the Gauss quadrature rules that are required by a stochastic
spectral simulator. The effectiveness of our proposed algorithm is verified by
both synthetic and practical circuit examples.Comment: Published by IEEE Trans CAD in May 201
Ultra-high-frequency piecewise-linear chaos using delayed feedback loops
We report on an ultra-high-frequency (> 1 GHz), piecewise-linear chaotic
system designed from low-cost, commercially available electronic components.
The system is composed of two electronic time-delayed feedback loops: A primary
analog loop with a variable gain that produces multi-mode oscillations centered
around 2 GHz and a secondary loop that switches the variable gain between two
different values by means of a digital-like signal. We demonstrate
experimentally and numerically that such an approach allows for the
simultaneous generation of analog and digital chaos, where the digital chaos
can be used to partition the system's attractor, forming the foundation for a
symbolic dynamics with potential applications in noise-resilient communications
and radar
Chaos From Switched-Capacitor Circuits: Discrete Maps
A special-purpose analog computer made of switched-capacitor circuits is presented for analyzing chaos and bifurcation phenomena in nonlinear discrete dynamical systems modeled by discrete maps *n + t = fan)-Experimental results are given for four switched-capacitor circuits described by well-known discrete maps; namely, the logistic map, the piecewise-linear unimodal (one-hump) map, the H é non map, and the Lozi map
Modeling the Flux-Charge Relation of Memristor with Neural Network of Smooth Hinge Functions
The memristor was proposed to characterize the flux-charge relation. We propose the generalized flux-charge relation model of memristor with neural network of smooth hinge functions. There is effective identification algorithm for the neural network of smooth hinge functions. The representation capability of this model is theoretically guaranteed. Any functional flux-charge relation of a memristor can be approximated by the model. We also give application examples to show that the given model can approximate the flux-charge relation of existing piecewise linear memristor model, window function memristor model, and a physical memristor device
Constant Rank Bimatrix Games are PPAD-hard
The rank of a bimatrix game (A,B) is defined as rank(A+B). Computing a Nash
equilibrium (NE) of a rank-, i.e., zero-sum game is equivalent to linear
programming (von Neumann'28, Dantzig'51). In 2005, Kannan and Theobald gave an
FPTAS for constant rank games, and asked if there exists a polynomial time
algorithm to compute an exact NE. Adsul et al. (2011) answered this question
affirmatively for rank- games, leaving rank-2 and beyond unresolved.
In this paper we show that NE computation in games with rank , is
PPAD-hard, settling a decade long open problem. Interestingly, this is the
first instance that a problem with an FPTAS turns out to be PPAD-hard. Our
reduction bypasses graphical games and game gadgets, and provides a simpler
proof of PPAD-hardness for NE computation in bimatrix games. In addition, we
get:
* An equivalence between 2D-Linear-FIXP and PPAD, improving a result by
Etessami and Yannakakis (2007) on equivalence between Linear-FIXP and PPAD.
* NE computation in a bimatrix game with convex set of Nash equilibria is as
hard as solving a simple stochastic game.
* Computing a symmetric NE of a symmetric bimatrix game with rank is
PPAD-hard.
* Computing a (1/poly(n))-approximate fixed-point of a (Linear-FIXP)
piecewise-linear function is PPAD-hard.
The status of rank- games remains unresolved
Optimal control of two qubits via a single cavity drive in circuit quantum electrodynamics
Optimization of the fidelity of control operations is of critical importance
in the pursuit of fault-tolerant quantum computation. We apply optimal control
techniques to demonstrate that a single drive via the cavity in circuit quantum
electrodynamics can implement a high-fidelity two-qubit all-microwave gate that
directly entangles the qubits via the mutual qubit-cavity couplings. This is
performed by driving at one of the qubits' frequencies which generates a
conditional two-qubit gate, but will also generate other spurious interactions.
These optimal control techniques are used to find pulse shapes that can perform
this two-qubit gate with high fidelity, robust against errors in the system
parameters. The simulations were all performed using experimentally relevant
parameters and constraints.Comment: Final published versio
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