A new algorithm for experimental circuit modeling of interconnection structures based on causality

A new algorithm is described for the circuit modeling of two-port interconnection structures starting from S-parameter measurements or simulations. The presented procedure is particularly useful in modeling interconnections with multiple discontinuities. The theory behind the method is based on the principle of causality. Step by step, a circuit model is proposed for each discontinuity and the corresponding parameter values are determined using the time-domain reflection and transmission response derived from the S-parameters. In this way, it is possible to obtain a circuit model for which each element is related to a certain physical part of the passive structure under test. The results show good-agreement between measured and modeled reflection and transmission waveforms.