Digital Predistortion Architecture With Feedback Channel Nonlinear Blind Identification and Compensation

Different from the forward channel interference signal, the feedback (FB) channel interference signal, including nonlinear distortion of an analog-to-digital converter (ADC) and RF downconverter, cannot be eliminated by the existing digital predistortion (DPD) system, which will seriously affect the performance of DPD system. The blind identification and compensation method of the nonlinear system in the FB channel is proposed to solve the problem of the DPD system. The approach is to utilize the adaptive algorithm to update the parameters of the compensation model, which is cascaded after the nonlinear distortion model, and keep the nonlinear transfer function be reversed to the being compensated model. Therefore, it can effectively eliminate or reduce the nonlinear distortion that needs to be compensated. The experiment shows that this method can obtain more accurate data for DPD.