The use of CMOS for microwave and RF design was broached to the microwave community in the early 1990s when GaAs was the technology of choice for designs in the UHF region and above [1]. Being able to design a CMOS RFIC (or any other RFIC technology device for that matter) is not simply a matter of getting time on a CAD workstation, inputting a certain circuit topology, and then letting a circuit optimization routine run for hours. An understanding of the underlying device operation is crucial to understanding the entire circuit operation. Time is well spent in the initial stages of an RFIC design by doing "back-of-the-envelope" calculations to determine if such a circuit is feasible before computer simulations verifying its operation are even started. In addition, these early-stage designs also aid in determining if unrealistic component or device values might be needed and what component or device variables need to be adjusted to provide a remedy to the problem. Once the computer simulation stage has been reached, intelligent adjustment of device parameters will ultimately yield functioning RFICs.

This chapter contains an overview of CMOS technology from both a fabrication as well as a device perspective. CMOS fabrication parameters and accompanying device layouts provide the basis for the estimation of RF equivalent circuit models for FETs and for their ultimate performance. This chapter focuses on linear small-signal equivalent circuit models for both n-channel and p-channel MOSFET devices. Numerous complex MOSFET models have been discussed in the literature,...