An Evaluation of the Class E Power Amplifier for Directed Energy Applications

This research evaluated the class E power amplifier for directed energy applications for scenarios that demand compact, efficient, and mobile microwave sources. The class E power amplifier was evaluated through simulation, design, fabrication, and experimentation. A GaN HEMT transistor was selected for the transistor in the class E PA design for its high frequency (single GHz) operation at relatively high output powers. A suboptimum class E power amplifier capable of operating at 30 W continuously at a drain efficiency of 82.9% was achieved for a center frequency of 2.3 GHz. The output power, drain efficiency, power added efficiency, and gain were measured for frequencies between 2 and 2.4 GHz, as well as RF input powers between 0 and 36 dBm. A drain efficiency over 60% was achieved while maintaining an average output power over 27 W for the entire 400 MHz frequency range. In addition to presenting a developed class E power amplifier and design methodologies, this work provides a comparison between the presented class E power amplifier and existing commercially available amplifiers designed for the same RF device. A simulation model was developed to accurately describe a suboptimum class E power amplifier’s output power and drain efficiency results within an absolute percent error of 5% for RF input powers greater than 30 dBm. In addition to evaluating the class E power amplifier, single and parallel configurations of the class E power amplifier were examined. This work seeks to expand the understanding of the class E power amplifier and its uses as a solid-state microwave source to offer a practical solution for developing compact, high-efficiency systems for directed energy applications.