Quarter-micron WSi/Au gate AlGaAs/InGaAs HJFETs for Q-band power applications

Quarter-micron T-shaped (WSi/plated-Au) gate AlGaAs/InGaAs HJFETs (heterojunction field effect transistors) for Q-band power applications are reported. An F/sub max/ of 170 GHz was achieved for the 100- mu m-gate-width device. F/sub max/ values of 115 and 90 GHz were realized for 400- and 800- mu m-gate-width devices, respectively, with 100- mu m unit gate finger width, by using Au plating for the gate metal formation to reduce the gate parasitic capacitance. An output power of 25 dBm was obtained with a linear gain of 6.6 dB at 40-GHz band.<>