Spectral Structure Analysis of FFT-based Digital Predistortion for Wideband 5G Applications

In this paper, a spectral structure analysis for the FFT-based subband digital predistortion is performed. This analysis consists in investigating whether the spectrum of the signal at the output of the power amplifier (PA) shows any particular structuring of the information. Various scenarios are investigated by simulation and validated by experiments, on a real PA. It is found that some spectral zones are more critical than others to maintain good linearization, which makes possible to reduce the requirements of the feedback path.