A large-signal switching MESFET model for intermodulation distortion analysis

This paper describes an improved large-signal model for predicting an intermodulation distortion (IMD) power characteristic of MESFET's in switching applications. The model is capable of modeling the voltage dependent drain current and its derivatives, including gate-source and gate-drain capacitors. The drain current and its derivatives are described by a function of a voltage-dependent drain conductance. The model parameters are extracted from a measured drain conductance versus gate voltage characteristic of an MESFET. This paper also presents a new fully symmetric equivalent circuit for switching MESFET's. The IMD power characteristics calculated with the use of the proposed method are compared with experimental data taken from a monolithic-microwave integrated-circuit single-pole double-throw switch, Good agreements over the large gate voltages and input power levels are observed.