A new temperature noise model of HFET with special emphasis on a gate-leakage current and investigation of the bias dependence of the equivalent noise sources

Considering the influence of a gate-leakage current on the noise performance of a microwave HFET, a novel approach for modeling the noise behaviour is presented. Based on an extended small-signal equivalent circuit of the HFET and three equivalent intrinsic noise temperatures the noise model allows the exact prediction of all noise parameters in a wide frequency range. The capability of the new model is demonstrated by noise measurements at room temperature and by comparison with a well established temperature noise model. Furthermore, for the first time an investigation of the bias dependence of the equivalent noise sources is carried out, which clearly shows the relationship of the equivalent noise voltage and noise currents to the RF- and DC-behaviour of HFET.