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 adopting a deep-recess structure. The structure of a 0.5-µm gate in a deeply recessed region with a cylindrical edge shape has enabled reduction of the source resistance to a half of that of conventional flat-type MESFET\´s. The noise figure was improved by more than 0.5 dB by this reduction of the source resistance, and less than 2.0-dB noise figure has been reproducibly obtained at 12 GHz. The best noise figures were 0.7 dB (14.9-dB gain) at 4 GHz and 1.68 dB (10.7-dB gain) at 12 GHz. The developed MESFET\´s were applied to two-stage amplifiers of 11.7-12.2-GHz band, and the noise figure obtained was 2.16 dB ( K) at room temperature and 1.94 dB ( K) at 0°C. This performance is good enough to replace some of parametic amplifiers.