A new approach to parameter extraction for on-chip symmetric transformers

A new approach to parameter extraction for on-chip symmetric transformers based on measured four-port S-parameters is proposed. Based on circuit analysis, open-loaded and short-loaded Y parameters are first used to derive the coupling parameters and all the other model parameters are derived from the corresponding analytical equations. As verified by a set of transformers fabricated on a standard 0.18 ¿m RFCMOS technology, by a careful comparison of S-parameters and other figure-of-merits between measured data and simulated data, the extracted parameters can predict the performance of on-chip transformers with a high precision up to 10 GHz. Since no iterations are needed in the fitting procedures, it can substantially increase the time efficiency of compact circuit modeling for on-chip transformers.