RF Energy System with Solid State Device

Abstract

Radio frequency (RF) energy is generated from electricity via either a vacuum tube or a solid state device. Owing to recent advances in solid state device technology, high power amplifiers can be applied in microwave ovens. A wide band gap material like gallium nitride (GaN) is expected to be a good candidate for high power RF energy applications. GaN is usually applied as a blue light-emitting diode but can also be employed for power devices (e.g., converter). Historically, in contrast to wide band gap semiconductor-based devices, conventional silicon (Si)-based solid state devices were considered incompatible for high power applications. Recently, however, Si-based laterally diffused metal–oxide semiconductors (LDMOSs) have been applied successfully in RF energy systems. When solid state devices are applied for a microwave heating system, like a microwave oven, new microwave heating methods are realized and new applicators can be used with solid state devices. Frequency, phase, and power of the microwaves can be broadly controlled with the solid state devices. It is a merit in microwave chemical science to estimate the effects of the microwave frequency. If frequency and phase of the microwaves in the solid state devices can be controlled, then the power distribution in the applicator and in space can also be controlled. In this chapter, recent research and development (R&D) status of solid state devices and the R&D of RF heating systems that employ solid state devices are reviewed.