EFFICIENT POWER COMBINING WITH D-BAND (110-170 GHZ) INP GUNN DEVICES IN FUNDAMENTAL-MODE OPERATION

D-band InP Gunn devices on diamond heat sinks with an n(+)n(-)n(+) str ucture and a graded doping profile in the active region were tested as free-running oscillators in individual resonant-cap full-height waveg uide cavities, Subsequently, matched oscillators were power-combined i n an in-line dual-cavity configuration, Combined radio frequency (RF) power levels of more than 300 mW at 106 GHz, 130 mW at 136 GHz, and mo re than 100 mW at 152 GHz were achieved. These RF power levels are the highest reported to date from either single or power-combined Gunn de vices at W-band and D-band frequencies, They correspond to combining e fficiencies of more than 80%, 86%, and more than 100% as wed as overal l dc-to-RF conversion efficiencies of 1.95%, 1.25%, and 0.90%, respect ively. Similar to oscillators with single devices, these power-combine d Gunn device oscillators exhibit good tunability and a phase noise of well below -100 dBc/Hz, measured at a frequency off the carrier of 50 0 kHz.