Measured microwave power performance of AlGaN/GaN MODFET

We report the first microwave power measurement on GaN FET's. At 2 GHz, a class A output power density of 1.1 W/mm with a power added efficiency of 18.6% was obtained on a 1 μm gate-length AlGaN/GaN MODFET. Mathematical simulation estimated that the transistor was operating at a channel temperature of 360/spl deg/C as a result of the poor thermal conductivity of the sapphire substrate. Despite this serious heating problem, the power output density still rivals GaAs MESFET's.