Modeling methodology of integrated five-port balun using two-port RF measurement

A comprehensive investigation of RF characteristics and RF modeling methodology of an integrated transformer/balun, fabricated by a 0.18 /spl mu/m mixed signal process, are presented. We proposed an improved lumped-element equivalent circuit and a three-step method to characterize and model the five-port balun by using a standard two-port RF measurement. The frequency dependence of inductance and resistance resulted from skin effects, proximity effects, and eddy current loss is considered in the lumped-element model. Both inverting and noninverting configuration were examined to enhance the model accuracy. The fitting results have good agreement with measurements over the frequency range of 0.1-6 GHz.