Derivation of accurate equivalent circuit models for multilayer periodic structures

This paper presents a procedure based on using the results of full-wave simulation of a multilayer filter to extract poles and zeros of admittance functions of a pi-network which represents that same structure. The functional form of the admittance is then used to arrive at a more accurate estimate of the equivalent circuit of the multilayer filter. Admittance values calculated through full-wave analysis are compared to the same results from a pole-zero extraction method in order to verify the validity of the latter.