Adaptive digital pre-distortions based on affine projection algorithm for WCDMA power amplifier applications

In this paper, we propose an adaptive digital pre-distortion (DPD) linearization based on an affine projection (AP) algorithm for WCDMA power amplifier applications. The performance of the affine projection algorithm is compared with the least-mean-square (LMS) algorithm and recursive-least-square (RLS) algorithm, respectively. From the compared results, the AP algorithm has the advantage of more efficient computational complexity than the other algorithms and also the convergence speed of the AP algorithm is faster than that of the LMS algorithm. An affine projection algorithm based DPD has been simulated and compared with a DPD using LMS and RLS algorithms, respectively. From the simulation results, the AP based DPD has achieved -62.5 dBc adjacent channel leakage ratio (ACLR) at the average output power of 44.7 dBm of power amplifier for WCDMA 1-FA test signal.