A Subcarrier-Level Digital Predistortion With Undersampled Feedback for Wideband OFDM Signals

作者：Mengyao Zhang, Zixuan Long, Tong Li, Wanzhi Ma, Qiang Xu, Ying Liu, Shihai Shao, Youxi Tang · 发表于：IEEE Microwave and Wireless Technology Letters · 年份：2026 · DOI：10.1109/lmwt.2026.3662818 · 研究领域：Advanced Power Amplifier Design、PAPR reduction in OFDM、Radio Frequency Integrated Circuit Design

The signal bandwidths in current 5G new radio (NR) and future 6G millimeter-wave bands reach 400 MHz or higher, posing significant challenges for digital predistortion (DPD). Two key difficulties arise: the feedback path must operate at a higher sampling rate, and accurately modeling the nonlinear distortion of wideband signals becomes increasingly difficult. Leveraging the characteristics of orthogonal frequency-division multiplexing (OFDM) signals, this letter proposes a subcarrier-level DPD with undersampled feedback for wideband signals. The proposed method reconstructs the frequency-domain (FD) subcarriers before aliasing from the undersampled feedback signal, enabling subcarrier-level frequency-selective predistortion. The experimental results for a 300-MHz OFDM signal demonstrate that the proposed method effectively suppresses the power amplifier’s (PAs) nonlinearity and reduces the feedback sampling requirement.