Analytical models of GaAs FET´s

We consider two analytical models for the calculation of the current-voltage characteristics of GaAs FET\´s. The first model which we call a "square law model" provides an accurate description of GaAs FETs with low pinchoff voltages (less than 2 V or so for GaAs devices with a 1-µm gate) and an approximate description of GaAs FETs with higher pinchoff voltages, The second model which we call a "complete velocity saturation" model accurately describes high pinchoff voltage devices (higher than 3 V or so for GaAs FETs with a 1-µm gate), but cosiderably overestimates the drain-to-source current in low pinchoff voltage FET\´s.