Adaptive Predistortion Architecture for Nonideal Radio Transmitter

Abstract

A nonideal radio transmitter both distorts the desired signal and generates spectral regrowth causing interference to adjacent channels. Predistortion techniques can be used to minimize these effects. The joint effect of different types of nonidealities is not straightforward to analyze and has not yet been studied in detail in the literature. In this paper, we demonstrate how to adaptively predistort a nonlinear high power amplifier and an I/Q modulator, and to compensate the frequency response of a radio frequency filter. The study considers the spatial order of adaptive predistorters and the temporal sequence of adaptation steps. In this way, both the system capacity and the power efficiency are improved.