An Overview of Fast DC–DC Converters for Envelope Amplifier in RF Transmitters

Over the past few years, RF power amplifiers are taking advantage of the switched dc-dc converters to use them in several architectures that may improve the efficiency of the amplifier, keeping a good linearity. The use of linearization techniques such as envelope elimination and restoration and envelope tracking requires a very fast dc-dc power converter to provide variable voltage supply to the power amplifier, but theoretically, the efficiency can be much higher than using the classical amplifiers belonging to classes A, B, or AB. The purpose of this paper is to analyze the state of the art of the power converters used as envelope amplifiers in this application where a fast output voltage variation is required. The power topologies are explored and several important parameters such as efficiency, bandwidth, and output voltage range are discussed. Some of these topologies are compared in terms of efficiency for a particular set of specifications.