Trap-related gain/phase jump of HFET power amplifiers

Using novel characterization techniques, output gain, and phase jumps (with respect to input frequency or input level) of multistage monolithic-microwave integrated-circuit power amplifiers were correlated with heterojunction field-effect transistor (HFET) drain-current kinks and negative gate resistances. Both physical and phenomenological models were used to explain the correlation through hole-trapping and self-biasing mechanisms. A remedy involving bias-stabilization diodes was experimentally verified. Other possible remedies are also discussed. The present conclusion can be extended to other metal-semiconductor field-effect transistor and HFET amplifiers with similar gain/phase jump problems