Digital Predistortion for Concurrent Dual-Band Transmitter

A new digital predistortion technique is proposed for power amplifier (PA) linearization in concurrent dual-band transmitters. In the considering system, dual-band signals are combined and amplified by a single wideband power amplifier (PA). The PA output signal is distorted by the cross-modulation between different band signals as well as their own inter-modulation. To design DPD for compensating for the nonlinearity of the concurrent dual-band transmitters, two independent feedback paths are required to convert the dual band PA outputs into baseband signals, respectively. However, it increases hardware complexity and cost. In addition it leads to the degradation of the linearization performance if any mismatch and/or offset between two feedback paths exist. In this paper, we propose a new DPD method requiring only a single feedback path. The proposed technique first estimates the dual-band PA characteristics using the single feedback path. Then the DPD parameters are extracted from the estimated PA characteristics. Computer simulation shows that the proposed technique can effectively linearize the PA and reduce the spectral regrowth at both bands.