Broadband Equivalent-Circuit Model for Uniform Multiconductor Transmission Lines

A passive and inherently stable Foster equivalent-circuit representation for uniform multiconductor transmission lines for moderate losses is presented. The method is based on an analytic eigenfunction expansion. An efficient model-order reduction is achieved by appropriate inductances that are extracted by a quasistatic approach. The order number of the truncated modal circuit is simply estimated, according to the required signal bandwidth. The accuracy and versatility of the suggested SPICE-compatible equivalent circuit is demonstrated by examples in frequency and time domain, including nonlinear terminations.