Analysis of the feedback envelope tracking linear class E power amplifier
Feedback envelope tracking amplifier is one technology to realize linear amplification for nonlinear class E power amplifier. In this paper, the basic architecture and frequency response of the feedback envelope tracking amplifier are analyzed in detail. And the analysis shows that the feedback envelope tracking loop can be implemented to satisfy the system's specifications of linearity and stability, if the bandwidth and the other design parameters are properly selected. The limited bandwidth and different time delay between the envelope path and the phase path can cause intermodulation distortions which deteriorate the linearity of the feedback envelope tracking amplifier, the model for the intermodulation distortions of the feedback envelope tracking class E power amplifier is analyzed compared to the envelope elimination and restoration transmitter. In order to evaluate the broadband performance of the feedback envelope tracking class E power amplifier, the error vector magnitude (EVM) specification is also analyzed, and the simulation results on EVM for WCDMA signal is given.
envelope tracking class e power amplifier envelope elimination restoration feedback linearization