Intrinsic GaAs MESFET equivalent circuit models generated from two-dimensional simulations

An accurate, physically based two-dimensional GaAs MESFET model is used to generate small-signal and large-signal equivalent circuit models useful for the evaluation of GaAs device structures and GaAs integrated circuits. The models and the simulation techniques described provide a useful means of evaluating RF performance on the basis of the physical properties of the FET. As an example, the small- and large-signal device characteristics are evaluated as a function of drain-source bias voltage and lattice temperature for a 0.8-μm gate length FET. The small-signal results show severe degradation of frequency response with increase of drain-source bias voltage because of a high electric field in the conduction channel. The large-signal results show that the decrease in RF power capability with temperature increase is primarily due to declining current capability with temperature