Scalable compact circuit model for differential spiral transformers in CMOS RFICs

A scalable and predictive compact circuit model is presented for differential spiral transformers in CMOS radio frequency integrated circuits (RFICs), which is made up of two coupled '2-pi' subcircuits for each inductor coil in the transformer. The values of the circuit elements are analytically calculated, and comparisons to a 2.5-dimensional full-wave numerical electromagnetic field solver reveal the accuracy of the model.