Modeling of nonuniform coupled transmission lines interconnect using genetic algorithms

Based on genetic algorithm (GA) in this paper we present a simple method to extract distributed circuit parameters of a multiple coupled nonuniform mi crostrip transmission lines from it's measured or computed S-parameters. Th e lines may be lossless or lossy, with frequency dependent parameters. Firs t a sufficient amount of information about the system is measured or comput ed over an specified frequency range. Then this information is used as an i nput for a GA to determine the inductance and capacitance matrices of the s ystem. The theory used for fitness evaluation is based on the steplines app roximation of the nonuniform transmission lines and quasi-TEM assumptions. Using steplines approximation the system of coupled nonuniform transmission lines is subdivided into arbitrary large number of coupled uniform lines ( steplines) with different characteristics. Then using modal decomposition m ethod the system of coupled partial differential equations for each step is decomposed to a number of uncoupled ordinary wave equations which are then solved in frequency-domain.