A 177-183 GHz High-Power GaN-based Frequency Doubler with over 200 mW Output Power

A GaN Schottky barrier diode (SBD) on SiC for frequency doubler applications was fabricated with a N-/N+ GaN stack of 200 nm / 1500 nm in thickness and 5×1017 cm-3 / 8×1018 cm-3 in doping densities, respectively. A cut-off frequency of 459 GHz at zero bias and reverse breakdown voltage of 15.4 V were obtained. A quartz glass circuit with flip-chip-mounted GaN SBDs was inserted between split-waveguide blocks to form a balanced frequency doubler. When driven with 2 W input power in pulsed mode, measured output power was 200-244 mW from 177-183 GHz with efficiency 9.5-11.8%.