A UHF-band digital pre-distortion power amplifier using weight divided adaptive algorithm

A look up table (LUT) type adaptive digital pre-distortion (ADPD) using a weight divided adaptive algorithm is presented. In this algorithm, an output signal of the power amplifier (PA) is used as a reference signal. Additionally, reference signal is divided by the coefficient of the LUT, so that the characteristics of the PA, such as temperature dependence, do not have influence on the convergence performances. The proposed algorithm is presented and the convergence condition is derived analytically. From the ADPD simulation, we present that the proposed algorithm is more stable than the conventional normalized least mean square (NLMS) algorithm. The developed UHF-band ADPD power amplifier achieved the intermodulation (IM) distortion of -50dBc and the PA efficiency of 18% at output power of 54.8dBm under an integrated services digital broadcasting for terrestrial television broadcasting (ISDB-T) OFDM signal.