A NEW NOISE MODEL OF HFET WITH SPECIAL EMPHASIS ON GATE-LEAKAGE

A new temperature noise model, including the influence of a gate-leakage current on the noise performance of a microwave HFET, is presented. Based on an extended small-signal equivalent circuit of the HFET and three equivalent noise temperatures the noise model allows the exact prediction of the four noise parameters in a wide frequency range. The validity of the new model is demonstrated by noise measurements at room temperature. It is shown that the three equivalent noise temperatures are frequency independent and that one of them (T-p) especially represents the noise contribution caused by the gate current I-G. The advantages of the new model are clearly demonstrated in comparison with a well established temperature noise model.