†a) , Yousuke TANIGUCHI † †b) , Masayoshi ODA † †c) , Yoshihiro YAMAGAMI † †d) , Yoshifumi NISHIO † †e) , Members, and Akio USHIDA †f) , Fellow SUMMARY Distortion analysis of nonlinear circuits is very important for designing analog integrated circuits and communication systems. In this letter, we propose an efficient frequency-domain approach for calculating frequency response curves, which is based on HB (harmonic balance) method combining with ABMs (Analog Behavior Models) of Spice. Firstly, nonlinear devices such as bipolar transistors and MOSFETs are transformed into the HB device modules executing the Fourier transformations. Using these modules, the determining equation of the HB method is formed by the equivalent sine-cosine circuit in the schematic form or netlist. It consists of the coupled resistive circuits, so that it can be efficiently solved by the DC analysis of Spice. In our algorithm, we need not to derive any troublesome circuit equations, and any kinds of the transformations.

Masayoshi ODA †a) , Nonmember, Yoshihiro YAMAGAMI †b) , Junji KAWATA † †c) , Yoshifumi NISHIO †d) , Members, and Akio USHIDA † †e) , Fellow SUMMARY We propose here a fully Spice-oriented design algorithm of op-amps for attaining the maximum gains under low power consumptions and assigned slew-rates. Our optimization algorithm is based on a well-known steepest descent method combining with nonlinear programming. The algorithm is realized by equivalent RC circuits with ABMs (analog behavior models) of Spice. The gradient direction is decided by the analysis of sensitivity circuits. The optimum parameters can be found at the equilibrium point in the transient response of the RC circuit. Although the optimization time is much faster than the other design tools, the results might be rough because of the simple transistor models. If much better parameter values are required, they can be improved with Spice simulator and/or other tools.

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Abstract-Solving combinatorial optimization problems is one of the important applications of the neural network. Many researchers have reported that exploiting chaos achieves good solving ability. However, the reason of the good effect of chaos has not been clarified yet. In this study, we investigate a performance of chaotic switching noise injected to the Hopfield neural network for quadratic assignment problems. By computer simulation we confirm that the chaotic switching noise is effective for solving quadratic assignment problems as well as intermittent chaos near three-periodic window.

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