Enhanced heterostructure field effect transistor CAD model suitable for simulation of mixed mode circuits

Abstract

We describe a new enhanced model for deep submicron heterostructure field effect transistors (HFET's) suitable for implementation in computer aided design (CAD) software packages such as SPICE. The model accurately reproduces both above-threshold and subthreshold characteristics of both n- and p-channel deep submicron HFET's over the temperature range 250-450 K. The current-voltage (I-V) characteristics are described by a single, continuous, analytical expression for all regimes of operation, thereby improving convergence. The physics-based model includes effects such as velocity saturation in the channel, drain-induced barrier lowering (DIBL), finite output conductance in saturation, frequency dispersion, and temperature dependence. The output resistance and the transconductance are accurately reproduced, making the model suitable for simulation of mixed mode (digital/analog) circuits. The model has been extensively verified against experimental data for two HFET technologies with gate lengths down to 0.3 /spl mu/m.