Distributed numerical modeling of dual-gate GaAs MESFETs

A one-dimensional, numerical gradual channel model is used to examine the behavior of dual-gate GaAs metal-semiconductor field-effect transistors (MESFETs). Distributed numerical models for dual-gate devices do not incur any significant changes over equivalent single-gate device models. Such distributed numerical models are very useful for examining the regions of operation of each channel and the internal field distributions, and they are applicable when the close proximity of the two gates couples the parameters of the individual channels and invalidates the modeling of the device as two channels in series. The author first derives simplified conditions for saturation and nonsaturation of each gated channel, using as a basis the series connection of two single-gate devices. This load-line approach has been found to be very useful for analyzing switching as well as RF bias conditions. Then the model and method used in a numerical gradual channel analysis of the dual-gate FET are described. The results of the analysis are presented and discussed