GaInAs MISFET Wideband Microwave Power Amplifiers

We present the first reported results on wideband GaInAs MISFET amplifiers. Using 1-μm-gatelength, 0.56-mm-gatewidth GaInAs MISFETs, we obtained: (a) a power output of 230±30mW (0.41 W/mm) with 33±3% power-added efficiency; (b) power output of 265±15 mW (0.47 W/mm) with 30±3% power-added efficiency, both over the 7- to 11- GHz band, and (c) a power output of 220 ±45 mW (0.39 W/mm) with 29 ±4% power-added efficiency over the 6- to 12-GHz band. With a 0.7-μm-gatelength GaInAs MISFET, a small-signal gain of 5±0.5 dB over the 11.4- to 22.6-GHz band was obtained. These data include all connector, bias network, and circuit losses. We also present an equivalent circuit model of 1-μm-gatelength GaInAs MISFETs based on S-parameter measurements. The model is essentially that for a MESFET with capacitors representing gate-to-source and gate-to-drain overlap capacitances added at input and output.