Optimised gate-drain feedback capacitance of W-band high gain passivated 0.15 /spl mu/m InAlAs/InGaAs HEMTs

A 0.15 /spl mu/m high gain, passivated, double-side-doped InAlAs/InGaAs HEMT with high uniformity over 2 inch InP substrates has been developed. A measured gain of 12.5 dB at 94 GHz was achieved at a drain bias of 2 V, giving an f/sub max/ exceeding 400 GHz. This high gain is mainly related to the extremely low gate-drain feedback capacitance, for which the physical origins are demonstrated. Using this technology, a single stage amplifier with 10.3 dB gain at 88 GHz and a distributed amplifier with 11 dB gain and 89 GHz bandwidth were fabricated.