A Complexity-Reduced Harmonic-Cancellation Digital Predistortion for HF Transmitters
Long Chen, Wenhua Chen, Xiaofan Chen, Jiaming Chu, Zhenghe Feng
Abstract
High-frequency (HF) transmitter implemented with the multioctave power amplifier (PA) is faced with the problem of high-order harmonics owing to the nonlinearity of the PA. In this letter, a complexity-reduced harmonic-cancellation digital predistortion (CR-HC-DPD) is proposed and a narrow pulse sampling (NPS) method is adopted for model identification. Compared with the previous HC-DPD scheme, the proposed CR-HC-DPD approach greatly decreases the number of sampling points used for modeling and, in turn, reduces the computational complexity. Measurement results on a class-AB GaN PA with a 600-Hz two-tone signal demonstrated that the CR-HC-DPD scheme canceled all the harmonics for being below -60 dBc with less than 5% complexity compared with the HC-DPD scheme.