A Joint Crest Factor Reduction and Digital Predistortion for Power Amplifiers Linearization Based on Clipping-and-Bank-Filtering
Résumé
A power amplifier (PA) operating point determines both its power efficiency and its linearity. A high operating point generally corresponds to a better efficiency but a poor linearity. The combination of Digital predistortion (DPD) and Crest factor reduction (CFR) enables the control of the PA operating point and the optimization of the trade-off between power efficiency and linearity. This paper proposes a novel technique for joint CFR/DPD adapted to single-carrier as well as multi-carrier signals. Compared to similar low-complexity approaches to PA linearization and efficiency enhancement, it provides better linearization performance especially when the PA operating point is chosen to be high. The CFR and DPD are here implemented as a single model so that the running complexity of the CFR is almost negligible. The CFR model coefficients are estimated through a new clipping-and-bank-filtering (CABF) method extended to multi-carrier signals. The approach is complete with a discussion on the choice of windows in the filter bank and the presentation of a multiple-step procedure to determine the best model structure. The proposed CABF-based joint CFR/DPD model is experimentally evaluated on test bench with a PA using single-carrier and 2-carrier 20 MHz long term evolution (LTE) signals as the stimulus.
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