17.6% Conversion Efficiency At 60 GHz with IMPATT Diodes ?

For the use in mobile systems high efficiency V-band IMPATT diodes for CW operation are developed. The design is based on a numerical large signal drift diffusion model. Flat-profile and low-high-low structures are simulated and the layers are grown by silicon molecular beam epitaxy. Solid circular and ring structures are fabricated. During the RF tests frequency dependent differences in the measured power levels using thermistor mounts and diode power sensors are observed: The RF tests yield a maximum efficiency of 17.6 % at 67 GHz with a double low-higlh-low diode measured with a manufacturer calibrated diode sensor. The efficiency drops to 13.5 % measured with a thermistor. With ring diodes high output powers (800 mW/59 GHz, no differences between different power sensors) at a very low junction temperature rise (140 K) can be obtained. At higher junction temperatures up to 1.4 Watt are achieved.