Analysis of Power Amplifier Modeling Schemes for Crosscorrelation Predistorters

Amplification of signals with fluctuating envelopes leads to distortion because of non-linear behavior of the Power Amplifier (PA). Digital Predistortion can counteract these non-linear effects. A crosscorrelation predistorter is a digital predistorter, based on the calculation of crosscorrelation functions using coarsely quantized signals. The crosscorrelation functions are transformed to the frequency domain and the spectra are used to calculate the coefficients of the predistorter memory polynomial. This method has reduced complexity and equivalent performance in comparison with existing schemes. In this paper, four alternative schemes to implement a crosscorrelation predistorter are analyzed. The PA characteristics can be determined either directly or indirectly using ’normal’ or orthogonal polynomials giving four alternatives. All four alternatives give significant reduction of Adjacent Channel Interference.