A Robust Digital Predistortion for LTE/5G Power Amplifiers Utilizing Negative Feedback Iteration

Release Date:2020-09-28  Author:LIU Xin, CHEN Wenhua, WANG Dehan, NING Dongfang  Click:

A Robust Digital Predistortion for LTE/5G Power Amplifiers Utilizing Negative Feedback Iteration

LIU Xin1, CHEN Wenhua1, WANG Dehan1, NING Dongfang2
(1. Tsinghua University, Beijing 100084, China;
2. RHP System Department, ZTE Corporation, Xi’an 710114, China )

Abstract: A robust digital predistortion (DPD) technique utilizing negative feedback iteration is introduced for linearizing power amplifiers (PAs) in long term evolution (LTE)/5G systems. Different from the conventional direct learning and indirect learning structure, the proposed DPD suggests a two-step method to identify the predistortion. Firstly, a negative feedback based iteration is used to estimate the optimal DPD signal. Then the corresponding DPD parameters will be extracted by forward modeling with the input signal and optimal DPD signal. The iteration can be applied for both single-band and dual-band PAs, which will achieve superior linear performance than the conventional direct learning DPD while having a relatively low computational complexity. The measurement is carried out on a broadband Doherty PA (DPA) with a 200 MHz bandwidth LTE signal at 2.1 GHz, and on a 5G DPA with two 10 MHz LTE signals at 3.4/3.6 GHz for validation in dual-band scenarios.
Keywords: 5G; digital predistortion; power amplifiers; negative feedback iteration

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