Lossless multi-way power combining and outphasing for radio frequency power amplifiers

Abstract

For applications requiring the use of power amplifiers (PAs) operating at high frequencies and power levels, it is often preferable to construct multiple low power PAs and combine their output powers to form a high-power PA. Moreover, such PAs must often be able to provide dynamic control of their output power over a wide range, and maintain high efficiency across their operating range. This research work describes a new power combining and outphasing system that provides both high efficiency and dynamic output power control. The introduced system combines power from four or more PAs, and overcomes the loss and reactive loading problems of previous outphasing systems. It provides ideally lossless power combining, along with nearly-resistive loading of the individual power amplifiers over a very wide output power range. The theoretical fundamentals underlying the behavior and operation of this new combining system are thoroughly developed. Additionally, a straight-forward combiner design methodology is provided. The prototype design of a 27.12 MHz, four-way power combining and outphasing system is presented, implemented, and its performance is experimentally validated over a 1OW-1OOW (10:1) output power range.