VERY HIGH-FREQUENCY SMALL-SIGNAL EQUIVALENT-CIRCUIT FOR SHORT GATE-LENGTH INP HEMTS

Small-signal equivalent circuit for short gate-length InP high electro n-mobility transistors (HEMT's) operating at very high frequency (HF) is proposed First, the extrinsic parameters of the equivalent circuit are determined using a cold HEMT but without forward gate bias. Then t he intrinsic parameters of the equivalent circuit are extracted, inclu ding the frequency dependence of some of them, A fast and accurate met hod based on least-squares regressions is presented to obtain the extr insic and intrinsic parameters from measured S-parameters. The improve d equivalent circuit accurately fits the S-parameters of 0.25-mu m InP HEMT's over the 500-MHz up to 40-GHz measurement bandwidth, for all g ate-to-source and drain-to-source voltages.