AlGaN/GaN power amplifiers for ISM frequency applications

In this paper we report on the development of an RF high power amplifier, based on normally-on AlGaN/GaN Heterostructure Field-Effect Transistors (HFETs) on semi-insulating SiC substrates. The amplifier is derived from a transistor with a total gate periphery of 120 mm that exhibits a breakdown voltage of 600 V. The transistor shows excellent DC characteristics up to 53 A in pulsed mode. The realized amplifier shows good performance in continuous wave (CW) mode with an output power of 139 W and an efficiency of 71% at a frequency of 13.56 MHz, respectively. In pulsed mode, the amplifier exhibits an output power of 431 W for a duty cycle of 10% which emphasizes the potential of the AlGaN/GaN material system for ISM applications. The comparison of the obtained values with silicon-based semiconductor devices furthermore shows the impressive advantages of AlGaN/GaN-based devices for parameters like current density and power density that are for AlGaN/GaN-based devices by an order of magnitude higher.