Fractional delay compensation in digital predistortion system

Delay mismatch between the input and output signals of power amplifiers (PAs) may lead to an erroneous assumption of memory effects. In adaptive digital predistortion (DPD) system, the delay mismatch affects the accuracy of coefficients estimation and degrades performance of the DPD system. In this paper, we reveal the impact of fractional delay mismatch, and analyze the relationship between delay mismatch and memory effects. The fractional delay compensation helps to reduce or eliminate the delay mismatch. Benefits of fractional delay compensation are provided through numerical analysis and experimental results.