DETERMINATION OF THE SMALL-SIGNAL PARAMETERS OF AN ALGAAS GAAS MODFET

The small-signal equivalent-circuit parameters of an AlGaAs/GaAs MODFET are derived by a first-order perturbation around the two-region DC model of an FET. The contribution of the AlGaAs electrons is included by using an accurate charge-control model. The charge-control model uses a mixed quantum-mechanical and classical approach to determine the density of channel electrons and AlGaAs neutral donors as a function of gate voltage. The model predictions show good agreement with experimental results for both low and high drain bias voltages.