Digital pre-distortion architecture for RF power amplifier based on affine projection algorithm

The design is reported of a digital pre-distortion (DPD) architecture based on the affine projection algorithm (AP) for RF power amplifiers operating in 900 MHz band. The linearity of the RF power amplifier with an OFDM signal is significantly improved by employing the proposed DPD system, where the look-up table method is used with nonlinear indexing. The proposed DPD with the AP algorithm is compared with that of the normalised least mean square algorithm, when applied to RF power amplifiers. Measurement shows improvement of the adjacent channel leakage ratio by 21 dB.