High-gain microwave GaN HEMTs with source-terminated field-plates

GaN HEMTs with field-plates connected to the source terminal have been developed for high-gain, high-voltage operation at microwave frequencies. Due to the reduced feedback capacitance compared to the gate-terminated field-plate structures, improvement in large-signal gain of 5-7 dB is obtained. Superior performance including 21-dB associated gain, 20-W/mm output power and 60% power-added-efficiency at 4 GHz and 118V bias, is achieved simultaneously. This translates to an extremely high voltage-frequency-gain product approaching 10 kV-GHz.