Channel-Selective Multi-Cell Digital Predistorter for Multi-Carrier Transmitters

This paper demonstrates a new channel-selective multi-cell processing predistortion technique that compensates for the nonlinearities of multi-carrier transmitters. The proposed technique uses independent processing cells to compensate for the intra-band and inter-band distortions of nonlinear transmitters. This frequency-selective feature of the proposed technique significantly reduces the minimum sampling rate requirements of analog-to-digital and digital-to-analog converters, which are a critical issue for conventional digital predistortion (DPD) techniques dealing with wideband signals. The proposed technique was evaluated with four-carrier (1001) and six-carrier (100001) WCDMA signals, using a nonlinear 10-Watt power amplifier. The performance of the proposed technique was compared with look-up table, multi-branch and recently proposed frequency-selective DPDs, in terms of adjacent-channel power ratios (ACPRs) and sampling rate requirements. The proposed technique improved the ACPR and the carrier-to-intermodulation power ratio (CIMPR) of the 1001 WCDMA signal by more than 13 dB and 10 dB, respectively.