Switched-mode high-efficiency microwave power amplifiers in a free-space power-combiner array

TLDR

The paper presents a design-oriented analysis of a microwave transmission-line class‑E amplifier. The authors verify theoretical class‑E amplifier equations through experiments and harmonic‑balance simulations, and compare the results to class‑A and class‑F amplifiers using the same MESFET devices. Experiments show 83 % drain efficiency and 80 % PAE at 0.5 GHz (0.55 W output), 81 % drain efficiency and 72 % PAE at 5 GHz (0.61 W output), and an integrated 5‑GHz class‑E array achieving 2.4 W output with 85 % power‑combining efficiency, 74 % DC‑RF conversion, and 64 % PAE.

Abstract

A design-oriented analysis of the microwave transmission-line class-E amplifier is presented. Experiments and harmonic-balance circuit simulations verify the theoretical equations which predict class-E-amplifier output power, maximum frequency of operation, and dc-RF conversion efficiency. Experimental results at 0.5, 1,2, and 5 GHz are presented. At 0.5 GHz, 83% drain efficiency and 80% power-added efficiency (PAE) are measured, with an output power of 0.55 W, using the Siemens CLY5 MESFET. These results are compared to a class-A and class-F power amplifier using the same device. At 5 GHz, 81% drain efficiency and 72% PAE are measured, with an output power of 0.61 W, using the Fujitsu FLK052WG MESFET. Finally, the 5-GHz class-E power amplifier is successfully integrated into an active-antenna array, demonstrating power combining of four elements with an 85% power-combining efficiency. At 5.05 GHz, the class-E power-amplifier antenna array delivers a total of 2.4 W of output power, with a dc-RF conversion efficiency of 74% and a PAE of 64%.