Adaptive Time Misalignment Compensation in Envelope Tracking Amplifiers

This paper considers the compensation of time misalignment between RF and envelope signals of envelope tracking (ET) amplifier. In particular, we propose methods to compensate the time misalignment and compare them to a previously presented method. Our simulation results indicate that the proposed methods give very accurate timing estimates. In the presence of optimal predistorter, we achieve with 90 percent probability adjacent channel power (ACP) level of -80 dB. With adaptive predistorters, we cannot see any degradation of ACP comparing to case of ideal timing. On the other hand, the proposed methods give roughly 10 dB better ACP than the previously presented method.