A 500 ?C Active Down-Conversion Mixer in Silicon Carbide Bipolar Technology.

This letter presents an active down-conversion mixer for high-temperature communication receivers. The mixer is based on an in-house developed 4H-SiC BJT and down-converts a narrow-band RF input signal centered around 59 MHz to an intermediate frequency of 500 kHz. Measurements show that the mixer operates from room temperature up to 500 ?C. The conversion gain is 15 dB at 25 ?C, which decreases to 4.7 dB at 500 ?C. The input 1-dB compression point is 1 dBm at 25 ?C and ?2.5 dBm at 500 ?C. The mixer is biased with a collector current of 10 mA from a 20 V supply and has a maximum DC power consumption of 204 mW. High-temperature reliability evaluation of the mixer shows a conversion gain degradation of 1.4 dB after 3-hours of continuous operation at 500 ?C. [ABSTRACT FROM PUBLISHER]