A new charge conserving capacitance model for GaAs MESFET's

Abstract

We present a new charge conserving capacitance model for Gallium-Arsenide (GaAs) metal semiconductor field effect transistors (MESFET's) based on the quasi-static approximation and a proper partitioning of the channel charge between the source and the drain terminals. A total of nine so-called transcapacitances were determined by taking derivatives of the various terminal charges with respect to the voltages at source, drain, and gate. The transcapacitances are nonreciprocal, i.e., C/sub ij//spl ne/C/sub ji/ when i/spl ne/j, and can be organized in a 3/spl times/3 matrix incorporating Kirchhoff's current law (charge conservation) and independence of reference. The present capacitance model is valid both above and below threshold, and shows good agreement with experimental data over a wide range of gate and drain biases. The model is analytical and suitable for implementation in circuit simulators.