Full Four-port Modeling and Characterization of On-chip Spiral Transformers for RFICs

Transformers integrated onto silicon substrates are characterized using a four-port network analyzer. S-parameters measured up to 20 GHz are used to study the trade-off between the device dimensions and the electrical performance of typical n:n transformers. A second order four-port compact model for integrated transformers is proposed. The evaluation of this model on devices in both standard four-port and two-port differential-to-differential configurations show a magnitude accuracy better than 8 % and a phase error less than 5 degrees in the frequency range from 300 MHz to 3 GHz.