RF CMOS is more than CMOS: Modeling of RF passive components

This paper details recent progress in modeling some RF CMOS passive components: inductors, transformers, and resistors. Many different topologies have been proposed for networks to model spiral inductors; these are analyzed and shown to trend toward reviving the one-segment (pi- or T-topology) approach. The need to account for the distributed nature of metal windings and coupling through a lossy substrate is emphasized. On-chip transformer models are discussed, and shown to need further development. Details of accurate physical modeling of polysilicon resistors, including nonlinearities and frequency dependence from both parasitics and self-heating, are provided.