High Power Microwave Signal Generation Based on Recursive Balanced Power Amplifier

This paper presents a high-power microwave oscillator using a recursive balanced amplification technique. The proposed architecture is configured by a balanced power amplifier (BPA) with class-AB operation and two feedback networks. Each feedback circuit consists of a phase shifter and a high-Q bandpass filter (BPF). The BPA consists of an input hybrid coupler (IHC) and an output hybrid coupler (OHC) to divide and recombine signals amplified through two power amplifiers (PAs) connected in parallel. The outputs of the OHC and the inputs of the IHC are connected to form a positive feedback loop for oscillation. The signal from each output of the OHC continuously and alternately feedbacks to each input of the IHC, resulting in recursive amplifications for high power oscillation. The proposed high power oscillator was designed at 915 MHz with the measured output power of 38.62 dBm. The measured DC-to-RF conversion efficiency was 44.43%. Furthermore, the measured phase noises were -118.42 dBc/Hz and -124 dBc/Hz at 10 kHz and 100 kHz offsets, respectively.