High-efficiency power oscillator using harmonic-tuned matching network

This paper presents a high-efficiency power oscillator, which uses LDMOS (Laterally Diffused Metal Oxide Semiconductor) transistor for high output power and a harmonic-tuned matching network to obtain high efficiency characteristic for RF power source application. A hair-pin resonator was designed and employed into the high efficiency power oscillator in order to improve phase noise characteristic and frequency selectivity. Measurement results show that output power of the power oscillator is 38.1 dBm, corresponding to a conversion efficiency of 73% at 981 MHz which is the highest efficiency reported in microwave power oscillator. Experiments performed with the hair-pin resonator show that output power is 36.9 dBm and conversion efficiency is 65%. Phase noises are measured to be 78.9 dBc/Hz and 103 dBc/Hz at 10 kHz offset without and with the hair-pin resonator, respectively.