A Low Noise FET Amplifier for Applications at 12 GHz

This paper describes the performance of a commercially available ¿ um gate FET chip in a "home made" package as a low noise amplifier at 12 GHz. The package can be easily inserted into and removed from an alumina microstrip circuit. A single stage circuit is described, which in conjunction with the FET and package yields a gain of 8 dB ± 0.5 dB from 10.7 GHz to 12.2 GHz with an associated noise figure of between 4.0 dB and 4.5 dB at room temperature. A reduction in ambient temperature to -40°C is shown to result in an improvement in the noise figure of approximately 1.0 dB with a change in gain of less than 0.2 dB. The cascading of three single stages with a simple balanced mixer is described. The performance of the resultant low noise x-band front end is given.