Combined power oscillator using GaN HEMT

This paper proposes a new configuration for power oscillator based on the combined power amplifier. The focus is on power combining as a oscillator structure with a positive feedback loop line. The proposed configuration consists of a harmonic-tuned combined power amplifier using two Gallium Nitride High Electron Mobility Transistors (CGH40025), 3dB Wilkinson divider/combiner, a directional coupler, an isolator, a coaxial line and mechanical phase shifters. The steady state oscillation occurs in a delay line feedback loop which length is adjusted to a oscillation frequency. The measured output power and conversion efficiency of the proposed oscillator are 46.8 dBm and 58 %, respectively, at 2.45 GHz with a drain bias voltage of 28 V.