Feedback-based digital predistorter for multi-bit delta-sigma transmitter

This paper proposes a feedback-based digital predistortion technique for multi-bit delta-sigma transmitters. This topology is based on a 3-bit delta-sigma modulator with a look-up table model of the power amplifier in the feedback loop. This feedback-based digital predistortion technique avoids the reverse modeling step found in conventional digital predistortion. Since the feedback loop is fully digitally implemented, the proposed architecture is not limited in terms of bandwidth, as is the case for conventional Cartesian feedback. System-level simulations and measurements have been carried out for evaluation of the performance of the proposed topology. It has been tested using a WiMAX signal, and the signal-to-noise-and-distortion ratio of the signal was improved by more than 20 dB and 10 dB in the simulation and measurement scenarios, respectively.