Loewner-based macromodeling with exact interpolation constraints

The so-called Loewner framework has been recently revitalized, providing an alternative approch to the more standard Vector Fitting scheme for building compact macromodels of interconnect networks. The matrix approximation process that is embedded in the Loewner method produces however models whose accuracy cannot be locally controlled at a desired frequency point. This paper proposes a simple solution for constraining the model response at any selected frequency value, with emphasis on the DC point. Two application examples illustrate the effectiveness of the approach.