Extended Frequency Range GaAs MESFETs using 0.3μm Gate Lengths

The use of GaAs MESFETs, based on 0.5μm gate length technologies, is now well established up to 18 GHz. However, system requirements are demanding either lower noise performance and/or higher frequencies. This paper describes the technologies necessary to fabricate devices with 0.3μm gate lengths, together with results of d.c. characterisation, detailed r.f. characterisation to 18 GHz and initial results up to 30 GHz. Noise figures of 1.2 dB, 1.5 dB, and 2.1 dB were obtained at 12, 14 and 18 GHz with associated gains of 12.5 dB, 11 dB and 9 dB. At 28 GHz a noise figure of 4.8 dB with 5 dB associated gain was achieved. The effects of cooling on device noise temperature is investigated.