Efficiency and linearity enhancements with envelope shaping control in wideband envelope tracking GaAs PA

In this paper we present the design of a power amplifier (PA) for envelope tracking (ET) operation based on the actual probability distribution function signal. The paper discusses the impact of envelope shaping i.e. the mapping of the drain modulated waveform to the RF output power, on system linearity and efficiency performance. The technique was applied to broadband ET PA designed around a GaAs HEMT at 940 MHz. The paper presents analytical treatment of the design technique along with characterization at device and system level. The adoption of a proper shaping function, improves ACP from -27.1dBc to -41.7dBc and increases device efficiency from 26.7% to 63.7%.