DC-Preserving Passivity Enforcement for $S$-Parameter Based Macromodels

Rational approximation of frequency responses is important for the modeling and design of microwave systems. An exact match of the dc value is crucial to ensure the accuracy and reliability of circuit and system simulations. This paper presents a novel approach to compute dc-compliant macromodels that are both accurate and uniformly passive at the same time. Several examples illustrate the effectiveness of the approach.