High‐accuracy filtering‐based envelope generation and digital predistortion for wideband envelope tracking power amplifier

Abstract

A high-accuracy filtering-based envelope generation technique for wideband envelope tracking power amplifiers (ET PAs) is proposed to improve PA efficiency with limited envelope bandwidth. It is achieved by optimizing the envelope generation block by employing three generalized rectification functions. The proposed envelope can be obtained by finding the proper coefficients in these generalized rectification functions. Furthermore, the digital predistortion can be employed to compensate for the nonlinearity and memory effect introduced by the proposed envelope. Experiments have been carried out on an ET system that is operated with the center frequency of 3.5 GHz, which have shown that the proposed technique can improve the PA efficiency by more than 2.2% with only 1.2× the modulated bandwidth compared to the state-of-the-art methods. The normalized mean square error can achieve −44.8 dB, and the adjacent channel leakage ratio can achieve better than −52 dBc. The proposed technique can improve the PA efficiency with limited envelope bandwidth compared to the state-of-the-art techniques, and the PA supplied by the proposed envelope can be linearized well, while it may cost more resources to find the proper coefficients of these three generalized rectification functions.