On Building D-Stable Macromodels

Vector Fitting (VF) is a widespread algorithm for building macromodels of complex linear time invariant electromagnetic components. One of the main reasons for its success is the possibility of easily enforcing model stability, a requirement that is essential for transient analysis. In this contribution, we generalize the standard VF stability enforcement through a novel rational fitting algorithm that enforces D-stability, by placing the macromodel poles within arbitrary convex regions of the complex plane. The method is practically applied to improve the performance of VF in the presence of noisy data and to remove unwanted out-of-band poles.