This paper describes a general computer program for the analysis and design of passive, active and non-linear lumped/distributed circuits. This program is particularly suitable for the analysis of active microwave networks and GaAs integrated circuits.

Compuier-Aided Design of Microwave Integrated Circuits

Encountering with a nonlinear second-order differential equation including ϵ
 r
 and μ
 r
 spatial distributions, while computing the fields inside inhomogeneous media, persuaded us to find their known distributions that give exact solutions. Similarities between random distributions of electric properties and known functions lead us to estimate them using three mathematical tools of artificial neural networks (ANNs), support vector machines (SVMs) and Fuzzy Logic (FL). Assigning known functions after fitting with minimum error to arbitrary inputs using results of machine learning networks leads to achieve an approximate solution for the field inside materials considering boundary conditions. A comparative study between the methods according to the complexity of the structures as well as the accuracy and the calculation time for testing of unforeseen inputs, including classification, prediction and regression is presented. We examined the extracted pairs of ϵ
 r
 and μ
 r with ANN, SVM networks and FL and got satisfactory outputs with detailed results. The application of the presented method in zero reflection subjects is exemplified.

Fast-forward solver for inhomogeneous media using machine learning methods: artificial neural network, support vector machine and fuzzy logic

A complete analysis of the sensitivities of shielded microstrips is presented. The sensitivity formulas form the basis for studying the effect of tolerances on the performance of these circuits. A set of sensitivity curves are given to help the design procedure. It is suggested that the position of the top cover can be adjusted to compensate for some of the effects of the manufacturing tolerances. Practical examples are given to support the suggested procedure.

Tolerance Analysis of Shielded Microstrip Lines (Short Paper)

This paper will report on the use of state-space (time varying) variables to anaylze and design microwave ICs, including not only linear passive and active elements, but nonlinear and time-varying elements.

Computer-aided design of nonlinear microwave ICs

A general and powerful technique for the analysis of networks containing lossy coupled transmission lines in inhomogeneous media is presented. The technique is suitable for computer-aided procedures and no restrictions on network topology are required. Good agreement was found between measured and calculated responses. One of the applications of the derived equations for lossy lines is the design of microstrip circuits on semiconductor substrates. The effect of varying the substrate resistivity has been investigated.

S.S. Bedair

Papers

State-space approach for the analysis of networks containing lossy coupled transmission lines in inhomogeneous media