Circuit design techniques for enhancing an efficiency of the high power feedback-type GaN-HFET (Gallium Nitride Heterojunction Field Effect Transistor) oscillator for use in the microwave oven are shown in this paper, focusing primarily on the harmonic terminations for high efficiency of power amplifiers, the coupling factor to feedback circuits and the insertion phase adjustment of feedback loops. With the use of these circuit design techniques, an output power of 263 W and an efficiency of 61.3% have been successfully achieved at 2.44 GHz.
SINGLE TRANSISTOR OSCILLATOR BASED ON PIEZOELECTRIC RESONANT NANOCHANNEL FOR OPERATION IN LIQUIDS