Spectra-Folding Feedback Architecture for Concurrent Dual-Band Power Amplifier Predistortion

This paper proposes a spectra-folding feedback (SFFB) architecture for digital predistortion (DPD) of concurrent dual-band power amplifiers (PAs). Conventional dual-band DPD contains a dual-branch feedback path to receive the PA output signals at respective bands. The proposed architecture, however, is constructed by a single-branch receiving path, so that the hardware expense (such as down converters, filters, or analog-to-digital converters) of the feedback path is significantly reduced. In this architecture, simple modifications are made to the down converter to allow the use of only one analog-to-digital converter. With the proposed signal processing in the baseband, the SFFB DPD can achieve comparative performance as the conventional dual-branch DPD. Experiments were performed using various configurations of LTE/LTE-Advanced (long-term evolution/long-term evolution advanced) signals of up to 80 MHz contiguous bandwidth and carrier spacing of 1 GHz. It is clearly shown by the experimental results that the proposed SFFB DPD can achieve satisfactory linearization performance, with significantly reduced hardware complexity.