Effects of crest factor reduction on the predistortion performance for multi-carrier 3G RF power amplifiers

In this paper, an analysis of the crest factor reduction effects´ on the predistortion performance of 3G multi-carrier power amplifiers is carried out. This study is performed at three different levels: the power amplifier level, the digital predistorter level, and the system level (linearized amplifier) for a Doherty amplifier driven by 3-carrier WCDMA signal. At the amplifier level, the use of crest factor reduction results in higher power efficiency, increased output power but also distortions. Experimental results show that this compromises the performance of the digital predistorter. The system level analysis highlighted that, in such case, the gained efficiency at the amplifier level will be lost after linearization. This is the first study that points out and experimentally reports the drawbacks of crest factor reduction when applied to digitally predistorted multi-carrier power amplifiers.