AbstractImpressive RF power performance has been demonstrated by three radically different wide bandgap semiconductor power devices, SiC MESFET's, SiC SIT's, and AlGaN HFET's. AlGaN HFET's have achieved the highest fmax 97 GHz. 4H-SiC MESFET's have achieved the highest power densities, 3.3 W/mm at 850 MHz (CW) and at 10 GHz (pulsed). 4H-SiC SIT's have achieved the highest output power, 450 W (pulsed) at 600 MHz and 38 W (pulsed) at 3 GHz. Moreover a one kilowatt, 600 MHz SiC power module containing four multi-cell SIT's with a total source periphery of 94.5 cm has been demonstrated.