Non-Quasi-Static Transient and Small-Signal Two-Dimensional Modeling of GaAs MESFET's with Emphasis on Distributed Effects

Abstract

We analyze, using a two-dimensional model, the operation of micron and submicron GaAs MESFET's under high-speed transient and high-frequency small-signal conditions. The effects of displacement currents, dipole due to negative differential mobility or current continuity, and two-dimensional transport are emphasized. The origin of delay effects, such as the phase delay incorporated in small-signal models, is explored in order to relate it to the behavior under switching conditions. Broad-band expressions for the extraction of a complete small-signal model are presented for the first time. Using the expressions derived, the variation of model elements with frequency and the effect of this on the unilateral gain of the device are studied. © 1993 IEEE