Experimental investigation of phase noise in high-efficiency class-E amplifiers

High-efficiency saturated class-E power amplifiers are well suited for transmitter applications where power efficiency must be maximized. At microwave frequencies, typical class-E power-added efficiencies are of the order of 50% compared to linear amplifier efficiencies of 30%. Although the highly saturated regime of class-E operation suggests degradation of the noise performance with respect to linear amplification, the relationship between the noise performance and efficiency is unknown. This paper presents a preliminary experimental investigation of phase noise performance in class-E amplifiers illustrating some of the tradeoffs between noise performance and efficiency in a GaAs MESFET amplifier with 24-dBm power output, designed for class-E operation at 4.6 GHz.