Bandwidth-constrained least squares-based model extraction for band-limited digital predistortion of RF power amplifiers

In this paper, a bandwidth-constrained least squares (LS)-based model extraction is proposed to enhance the linearization performance of band-limited digital predistortion (DPD) for RF power amplifiers (PAs). By laying frequency bandwidth constraints on the conventional LS-based model extraction, the modified extraction method is adapted for the band-limited DPD scenario. Compared to the conventional LS-based model extraction, the proposed bandwidth-constrained LS based approach can provide an accurate model extraction with much narrower bandwidth. In order to evaluate the performance, experimental validation was carried out on a wideband Doherty PA, which was designed for 3G/4G wireless communication systems. By applying the proposed approach, the ACLR achieved below -55 dBc for 40 MHz 8-carrier UMTS signal within only 80 MHz observation bandwidth.