Comparative Study of Estimation Algorithms for Predistorter Coefficients of GaN Power Amplifier

The purpose of this paper is to compare two estimation methods when identifying the coefficients of the Simplified Volterra Series (SVS) model, in order to linearize a class AB GaN Power Amplifier (PA) driven by a 20-MHz LTE-A signal. First, a Digital Predistorter (DPD) design using the cholesky decomposition based inversion method and the Least Square QR (LSQR) algorithm is carried out, and next the performances of each method are analyzed in terms of computational complexity and suppressing distortions capability. The co-simulation test results show that the LSQR performs better than Cholesky decomposition in terms of Adjacent Channel Power Ratio (ACPR) and Normalized Mean Square Error (NMSE) by a margin of 3 dB and 4 dB, receptively.