Digital predistortion for 5G wideband power amplifiers using multiple band-limited feedback signals

Abstract

This paper presents a digital predistortion (DPD) solution using multiple band-limited feedback signals for the characterization of wideband power amplifiers (PAs). By acquiring the feedback signals with band-limited filter and several different local oscillator frequencies, the feedback bandwidth is constrained to be much less than the bandwidth of input signal. Then the PA's forward model is extracted with these feedback signals jointly without spectrum combination, and the complete PA output without information loss can be restored based on the model parameters. Experimental results validate satisfied linearization performance on a 20GHz amplifier with 200MHz input signal, when the feedback bandwidth is constrained to 98.304 MHz. Thus, the bandwidth of the feedback loop can be reduced drastically in the presented method, which may be a linearization solution for the future 5G wideband scenarios.