Analysis and circuit modeling of on-chip transformers

Abstract

We present circuit topologies and fitting methods that accurately represent on-chip transformers over a frequency sufficient for cellular and PCS circuit analysis. Starting with an S-parameter matrix, obtained through measurement or electromagnetic (EM) simulation, we find an equivalent lumped-element circuit model with minimum fitting error. Consideration is made for the passivity of the model. Examples are shown that include measurements, EM simulation, and equivalent circuit models.