Wide-band GaInAs MISFET amplifiers

The authors present the first reported results on wideband GaInAs MISFET amplifiers. Using 1- mu m-gate-length, 0.56-mm-gate-width GaInAs MISFETs, they obtained: (a) a power output of 230+or-30 mW (0.41 W/mm) with 33+or-3% power-added efficiency; (b) a power output of 265+or-15 mW (0.47 W/mm) with 30+or-3% power-added efficiency (both over the 7-11-GHz band), and (c) a power output of 220+or-45 mW (0.39 W/mm) with 32+or-4% power-added efficiency over the 6-12-GHz band. With a 0.7- mu m-gate-length GaInAs MISFET, a small-signal gain of 5+or-0.5 dB over the 11.4-22.6-GHz band was obtained. These data include all connector, bias network, and circuit losses. The authors present an equivalent circuit model of these MISFETs based on S-parameter measurements. The model is essentially that of a MISFET with capacitors representing gate-to-source and gate-to-drain overlap capacitances added at input and output. >