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.