Extraction of intrinsic AC parameters of mm wavelength GaAs HEMTs from measured DC characteristics

Abstract

This paper discusses the estimation of intrinsic small signal parameters of GaAs High Electron Mobility Transistors (HEMTs). In the proposed technique observed DC characteristics of submicron GaAs HEMTs are first simulated by using a four-parameter non-linear model. Intrinsic AC small signal parameters of the device are then estimated by using DC experimental data. The study showed that intrinsic small signal parameters of an HEMT can only be estimated, to an acceptable accuracy, if the device Schottky barrier conditions are taken into account. The effects of non-ideal Schottky barrier response and the parasitic FET on the device transconductance, output conductance, channel resistance and Miller capacitances have been evaluated. In general, it has been shown that the technique is accurate as well as efficient in estimating AC parameters of GaAs HEMTs by using their DC characteristics, and could be employed in device simulation software.