Digital Predistortion of a RF Power Amplifier using a Remote Closed Loop Estimator

Abstract

A remote closed loop estimator that optimizes digital predistortion (DPD) of RF power amplifiers (PAs) is proposed. The observation path receiver used to measure the output of the PA is remote from the transmitter, coupled using a RF link. To make it work, the estimator must compute the DPD coefficient error using only the output signal. This differs from a standard closed loop estimator that uses time-aligned captures of both the input and output signals. It is shown that the remote closed loop estimator is robust to equalization error within the observation path.