Super low noise GaAs MESFET´s with a deep recess structure

Super low noise GaAs MESFET´s for replacement of parametric amplifiers have been successfully developed by utilizing an electron beam lithography technique and by adopting a deep recess structure. The noise figure of less than 2.0 dB at 12 GHz has been reproducibly achieved by the structure of a 0.5 µm gate in a deeply recessed region because the source resistance was reduced to a half of that of a conventional flat type MESFET by this structure. The best noise figure was 1.68 dB with 10.7 dB associated gain at 12 GHz. The developed MESFET´s were applied to 2- stage amplifiers of 11.7-12.2 GHz band, and the noise figure obtained was 2.16 dB (Te: 185 K) at the room temperature and 1.94 dB (Te: 163 K) at 0°C. This performance is enough to replace some of the parametric amplifiers.