Bias dependence of RF power characteristics of 4H-SiC MESFETs

4H-SiC MESFETs have been fabricated, packaged, and RF power tested under a wide range of bias conditions, ranging from Class A to Class B gate bias, and from 10 V to 50 V drain bias. Peak device performance included output power of 30.2 dBm (3.1 W/mm) at the 3 dB compression point and 38.9% power added efficiency in Class A operation, and 65.7% power added efficiency with 28.8 dBm (2.27 W/mm) maximum output power under Class B conditions. We believe this to be both the highest power density and the highest power added efficiency reported for a SiC MESFET.