Adaptive Digital Predistortion for Power Amplifier Linearization

The new radio communication systems move toward the use of non-constant envelops modulations and toward the application of spread spectrum techniques. The modulated output envelops of such signals are strongly dynamic and so, the influence of the nonlinearities of the transmitters are not negligible. A solution consists of correcting the amplifier while associating with it a linearization device so that the whole amplifier-linearizer system behaves in a quasi-linear manner up to practically the power of saturation. The main part is dedicated to the study of a new adaptive digital predistorter that can be applied to wide band signals used in third generation systems. After a state of the art of the predistortion system a new technique or improvement of adaptation techniques are proposed and estimated by simulation. The influence of the main sources of imperfections on the system is analyzed. The work also compares the complexity of the different approaches of predistortion by LUT, polynomial predistortion without memory or with memory.