This is a book about the modeling of RF power transistors, in particular, field effect transistors, or FETs. In it, we shall describe characterization and measurement techniques, analysis and synthesis methods, the model implementation in the simulator, and the verification and validation techniques that are needed to produce a transistor model that can be used with confidence by the circuit designer.

The demand for accurate transistor models for RF and microwave circuit design has increased as a result of the more stringent requirements that are placed upon power amplifier and transmitter designs by the customers and regulating agencies. Modern power amplifiers for communications systems are tightly specified in terms of the required linearity performance, multichannel capability, bandwidth, and so forth. At the same time, there is a quest for higher-efficiency operation, to be realized perhaps by inherently nonlinear modes of operation, such as Class D, E, F, and others. These demands are generally conflicting, and the designer is faced with a multidimensional compromise. The traditional high-frequency design approaches of ‘cut-and-try’ are simply not appropriate for the design of RF power amplifiers for complex signal communications systems, and the designer must turn to computer-aided design (CAD) techniques and circuit simulation to optimize his design to meet the specifications. This increased use of CAD methods for RF power amplifier design places a greater reliance on the availability of accurate transistor models for simulation.