Effect of demodulator errors on predistortion linearization

Any errors in a linearization system for power amplifiers will affect linea rization results. In this paper the effect of the demodulator errors on a f ew adaptive predistortion techniques is studied. The investigations are foc used on the complex gain predistorter [3] and the mapping predistorter [4]. The analyses and simulations show that in the complex gain predistorter on ly a DC offset will affect the Adjacent Channel Interference (ACI). Gain im balance and phase imbalance of the demodulator have no effect on the ACI in the complex gain predistorter system. In the mapping predistorter system, although the predistorter was also misadjusted because of errors, the ACI w ill not be deteriorated. But due to these errors, linear distortions will e merge in both systems and Bit Error Rate (BER) of both systems will be degr aded. The conclusions obtained in this paper can be used to guide the predi storter design. According to these guidelines the design process can be sim plified and the ACI can be improved.