Noise performance of gallium arsenide field-effect transistors

After a brief review of the noise-generating mechanisms intrinsic to the GaAs FET, an enumeration is given of the various parasitic elements associated with the FET which affect the noise performance. These elements include, among others, the gate metallisation and source contact resistances, drain-gate feedback capacitance, and source lead inductance. Numerous graphs are presented to illustrate the effects of these elements and the various design parameters on the noise performance. A comparison is made between the theoretically predicted and the measured noise performance of microwave GaAs FET´s. The best state-of-the-art noise performance as reported by various laboratories is illustrated graphically for single-stage and multistage FET amplifiers. Finally, some speculation is attempted in regard to the possible reductions in noise figure to be expected from technological and design improvements of GaAs FET´s.