A capacitance model for GaAs MESFET's

We present a new analytical model for small signal capacitances of GaAs MESFET's. This model may be used for epitaxially grown as well as ion-implanted FET's because the effects related to the nonuniform doping profile are included. We also take into account backgating, capping, velocity saturation in the conducting channel, and possible Gunn domain formation in the channel at the drain side of the gate. The model explains complicated voltage dependences of the gate-source and gate-drain capacitances of GaAs microwave FET's and is in fair agreement with the experimental results. This analytical model is quite suitable for the computer-aided design of GaAs microwave FET's and integrated circuits.