A reduced complexity digital predistorter with a single common feedback loop for concurrent multi-band power amplifiers

This paper proposes a reduced complexity digital predistorter (DPD) with a single common feedback loop for concurrent multi-band power amplifiers (PAs). Some multi-band DPD schemes with a single common feedback loop have been proposed; however the conventional DPD scheme requires additional complexity for calculating PA modeling coefficients and separating a feedback signal obtained by overlapping multiband feedback signals in the frequency domain. The proposed DPD can reduce complexity by avoiding the additional complexity for separating the overlapped feedback signals. The proposed DPD scheme compensates for nonlinear distortions with lower complexity using estimated feedback signals obtained by subtracting the signal transmitted on another band from the overlapped feedback signal. It is revealed that the proposed DPD scheme achieves a more than 63% reduction in complexity without sacrificing the DPD linearization performance.