A GaAs MESFET large-signal circuit model for nonlinear analysis

A large-signal GaAs MESFET model for performing nonlinear microwave simulations with SPICE or the Microwave SPICE and Libra programs is described. The model includes accurate analytical representation of the dependence of DC transconductance, gate-to-source capacitance, gate-to-drain capacitance, input and noise resistances, and drain-to-source resistance on operating gate-to-source and drain-to-source voltages. The model also functions as a master linear model that accurately replicates measured microwave S-parameters at arbitrarily chosen bias points within the transistor´s useful operating C-V range. Microwave SPICE harmonic distortion simulations with the model compare favorably with measurements for an NEC NE71000 GaAs MESFET.<>