High-Efficiency 5-kW, 1500-MHz Solid-State Power Amplifier

70034 Accelerators for nuclear physics research currently use vacuum-tube devices (klystrons) to generate high-power signals at 1500 MHz. As a result, they are subject to low efficiency, aging effects, low reliability, short life, and high operating expense. This project will develop an improved power amplifier by utilizing wide-bandgap semiconductor devices and optimized power combining. The wide-bandgap semiconductor devices (SiC and GaN) will allow the production of significant power at microwave frequencies. The optimized combining strategy will maximize the efficiency in converting dc-input power to RF-output power. Phase I will define system requirements and determine the capabilities of SiC and GaN RF-power transistors. Trade-offs among different high-efficiency power implementations will be evaluated and the preferred concept will be tried in a small prototype amplifier. Finally, power-combiner strategies will be reviewed and an architecture for the 5-kW amplifier system will be developed. Commercial Applications and Other Benefits as described by the awardee: Nuclear-physics accelerators should benefit from reduced heat dissipation and reduced operating/maintenance costs. Adaptations of the power amplifiers should find use at UHF and lower microwave frequencies, including RF lighting, RF heating, base-station transmitters for cellular communication, and military communication/jamming.