A New Loop-delay Estimation Algorithm for Amplifier Predistortion System

Predistortion technology is an adaptive, low cost and potential linearization method. Proper loop-delay estimation and compensation are important preconditions for ensuring the predistorter working well. But traditional loop-delay estimation algorithms are vulnerable to the amplifier's memory and nonlinear distortion. In this paper, based on the relationship between the system loop-delay and the amplitude of predistorter error output, we propose a new loop-delay estimation algorithm which improves the algorithm estimation accuracy in memory nonlinear distortion. Simulation results show that the NMSE after the predistortion is very close to the ideal one and a good power spectral density (PSD) performance is achieved. The new algorithm realizes the predistorter and the loop-delay estimation working simultaneously that maintains the reliability and continuity of signal transmission.