An equivalent lumped-circuit model for on-chip symmetric intertwined transformer

A physics-based equivalent lumped-circuit model for on-chip symmetric intertwined transformer is presented in this paper. This model accurately predicts the skin effect and proximity effect of the primary and secondary coils inductors over a wide-frequency range using a ladder `4-element´ structure, respectively. One transformer loop and two RC networks are used to model the substrate loss related to substrate eddy current loss and capacitive and reactive effect of lateral substrate coupling. Two transformers were fabricated on a standard 0.18-um 1P6M RF CMOS technology to further verify the accuracy of the proposed model.