COMPUTER-AIDED OPTIMIZATION OF BROAD-BAND NONLINEAR MICROWAVE INTEGRATED-CIRCUITS WITH THE AID OF ELECTROMAGNETICALLY GENERATED LOOK-UP TABLES

The direct numerical optimization of nonlinear microwave circuits by h armonic-balance analysis coupled to electromagnetic simulation is a fo rmidable computational task, even if advanced algorithmic concepts suc h as the space-mapping technique are exploited. In order to obtain a r easonable compromise between accuracy and design time, the most CPU-ti me-intensive components may be extracted from the circuit and separate ly analyzed by electromagnetic techniques. The results are then organi zed in the form of look-up tables that are coupled to the optimization process by means of suitable interpolation algorithms. The article di scusses the generation of such a family of look-up tables for square s piral inductors, and their use in nonlinear circuit optimization. It i s shown that the range of inductance values typically of interest for RF/microwave design can be covered by two-dimensional tables depending on frequency and on one geometrical parameter only. The resulting opt imization process is fast and well behaved, and can normally achieve t he same circuit performance produced by a design approach based on ide al lumped inductors. (C) 1997 John Wiley & Sons, Inc.