Proposal for a transmission line analytical method using multi‐objective optimization

Abstract

SUMMARYRecently, simulations are increasingly important in the design and development of high-speed transmission circuits, and simulations of high-precision transmission lines based on actual measurements are essential. Therefore, in this paper, the authors propose a method of determining transmission line characteristics for implementing high-precision transmission simulations from transmission line measurement results. The authors had previously proposed a method of creating an equivalent circuit model from transmission line characteristics. Combining that method with the method proposed in this paper enables high-precision simulations based on actual measurements to be performed with a circuit simulator such as SPICE according to a procedure that (1) measures transmission lines, (2) determines transmission line characteristics, and (3) creates an equivalent circuit model. The method that is proposed in this paper for determining transmission line characteristics has two features: (1) fitting that simultaneously uses actually measured frequency characteristics and time-based response waveform and (2) fitting that uses multi-objective optimization. Specifically, the authors apply multi-objective optimization using a genetic algorithm to simultaneously fit multiple sets of frequency characteristics and time-based response waveforms. As a result, trial-and-error with weightings among the characteristics is unnecessary and fitting is automated. The results when the proposed method was actually verified by using micro-strip lines clearly showed that a high-precision simulation could be performed with respect to both the frequency and time axes.