Microwave noise parameter modeling of a GaAs HEMT under optical illumination

This article presents the experimental results of the modeling of noise parameters for a GaAs HEMT under light exposure. The noise model is based on the equivalent-circuit representation expanded by assigning an equivalent noise temperature to each resistor. To take into account for the significant increase of the gate current under light exposure, two resistances with the associated noise temperatures have been added at the input and feedback of the intrinsic section of the circuit. The validity of the developed technique has been confirmed by the achieved good agreement between measured and simulated microwave noise parameters with and without optical illumination.