EFFICIENT IMAGE THEORY FOR ELECTROMAGNETIC-FIELD MODELING IN PCB

Computing the values of the capacitances for an equivalent circuit mod el of a PCB is a very CPU-intensive task. The time taken for this is d ominated by the time taken to compute the scalar potential due to a pa rticular charge distribution, which is linearly proportional to the nu mber of terms in the image series used to obtain the potentials. This paper describes several possible methods for speeding up the computati on of scalar potentials by reducing the number of terms required in th e image series for a given accuracy. The best of these methods reduced the number of images required by up to a factor of 400 for the partic ular PCB geometries examined. The improvements are most marked where t he original expressions were slowest to converge, which is particularl y useful. The fitting procedure described is a once only computation f or a particular layer structure, and does not have to be repeated for every simulation run, giving further savings. The results of this work have been incorporated in the program FASTERIX, which is capable of s imulating electromagnetic fields for much more complex layouts than ot her simulators.