An accurate digital predistorter based on a generalized two-box model for LTE applications

In this paper, a novel generalized two-box model is proposed to model digital predistortion and radio frequency power amplifiers in modern wireless transmitters and intelligent systems. The new model consists of two boxes that the first box emulates the static behavior of the power amplifier and the second box introduces more FIR filters considering linear and nonlinear memory effects. The coefficients of a Volterra power amplifier model have been exactly extracted using a least square method and those of predistortion have been identified by applying an indirect learning structure. Finally, the performance of digital predistortion has been demonstrated using the simulation of the power amplifier and the digital predistortion excited by a 5MHz LTE signal in the advanced design system software. According to the simulation results, the criterion of adjacent channel power ratio (ACPR) has been declined around 35dB and the spectral regrowth of the power amplifier has been reduced. The proposed generalized two-box model has achieved the better performance compared to state of the art digital predistortion models.