Improvements in Low Noise Gallium Arsenide Fets for X-Band Applications

A single stage narrow band amplifier operating at 8 GHz has been developed with a noise figure of 2.2 dB and associated gain of 7.0 dB. Correcting for microstrip losses yields a device noise figure of 1.9 dB and associated gain of 7.6 dB. This result has been achieved with 1.3 μm gate length devices fabricated on a three layer material structure involving the growth of a high resistance buffer layer, an active n layer and an n+ contacting layer. Assessment techniques to determine device and material quality from DC FET observations will be described and a comparison of DC light sensitivity for different material structures will be made.