SPICE-COMPATIBLE MICROWAVE MODEL OF AN OPTICALLY CONTROLLED HIGH-ELECTRON-MOBILITY TRANSISTOR

The effect of optical illumination on the microwave characteristics of an optically gated AlGaAs/GaAs HEMT has been studied theoretically. T his article describes an integral approach to the problem which includ es the calculation of the capacitance and the sheet concentration of t he two-dimensional (2D) electron gas in the illuminated condition. The changes in the various intrinsic parameters of the device under the i lluminated condition have been utilized to calculate the Y-parameters of the device at microwave frequencies. The lumped circuit model of th e device in the illuminated condition has been obtained with the vario us components determined from the Y-parameters. The attractive feature of the present model is that it is fully compatible with commonly use d circuit simulation packages like SPICE. (C) 1996 John Wiley & Sons, Inc.