Q-band (26-40 GHz) GaAs FETs

Gallium arsenide FETs demonstrating maximum gains of 4 dB at 40 GHz have been fabricated using combined photolithographic and electron beam lithographic techniques. The device structure has been optimised for high frequency performance. An equivalent circuit model has been derived from low frequency S-parameter data demonstrating good agreement with measured high frequency results. Device noise figures of 1.2 and 2.1 dB have been demonstrated at 12 GHz and 18 GHz respectively. At 27 GHz a substrate noise figure (i.e. including substrate losses) of 3.6 dB with 5.0 dB associated gain has been obtained. Low temperature (+77°K) noise figures of 0.3dB have been obtained at 14 GHz.