High-performance oscillators and power combiners with InP Gunn devices at 260-330 GHz

InP Gunn devices with graded doping profiles were evaluated for second-harmonic power extraction above 260 GHz. The best devices generated radio frequency (RF) output power levels of 3.9 mW at 275 GHz, 4.8 mW at 282 GHz, 3.7 mW at 297 GHz, 1.6 mW at 329 GHz, and 0.7 mW at 333 GHz with corresponding dc-to-RF conversion efficiencies of 0.24%, 0.31%, 0.32%, 0.19%, and 0.07%. The highest observed second-harmonic frequency was 345 GHz. Two devices each in an in-line power combining circuit generated 6.1 mW at 285 GHz and 2.7 mW at 316 GHz with combining efficiencies of more than 65%.