A Brune's two-port process applied to lumped element filter modeling

A two-port Brune's process is applied to generate a lumped element equivalent circuit model of a Chebyshev filter of order 11 based on measured data. From the measured S parameters a rational function description is obtained by a system identification procedure applied on tabular data. This procedure consists of two main steps. The first one is a physical model order determination which can be done by using the information criteria. The second one is a linear model parameters estimation with the vector fitting method. From this rational function description the Brune's lumped element equivalent circuit is directly derived. The Brune's process allows to establish a lumped element circuit model accounting also for the circuit losses and exhibiting positive circuit elements only.