High-power AlGaN/GaN FET-based VCO sources

The first report of multi-watt AlGaN/GaN FET-based voltage-controlled oscillators (VCO's) with high efficiency is presented. Varactor-tuned oscillators implemented using distributed networks oscillate at 3 GHz with high output power (2.7 w), high efficiency (27%), high supply voltage range (3.5 V to 30 V) and high tuning bandwidth (13%) over a control voltage range from 1 to 9 V. The measured output power and circuit efficiency are examined as a function of supply voltage. These results indicate high-power AlGaN/GaN-based VCO's may he used as high-efficiency sources for radio communications.