A Single Feedback Architecture for Dual-Band Digital Predistortion with Under-Sampling Technique

This paper applies a single feedback digital predistortion (DPD) architecture with under-sampling technique to linearize concurrent dual-band power amplifiers, where the dual-band output is treated as a single wideband signal to be down-converted and sampled with significantly reduced sampling rate. A wideband class-AB GaN power amplifier excited by dual-band LTE signal with total bandwidth of about 320 MHz was tested to validate the proposed approach. Experimental results show that when the sampling rate is reduced by more than 6 times, the new method can improve ACPR performance by about 16dB. Moreover, even aliasing exists in the output after under-sampling, the method still works well.