A new technique for adaptation of linearizing predistorters

A technique for the adaptation of a predistorter is demonstrated. This technique does not provide real-time adaptation but only adjusts to the drifting characteristics of the power amplifier. This technique is based on the ability to sample the out-of-band power and use this scalar quantity to adjust the predistorter coefficients. The predistorter could be implemented in analog form or digitally. Analog predistorters can take the form of cubic predistorters consisting of antiparallel diodes with gain and phase adjustments, intermediate frequency analog polynomials, etc. Digital predistorters using this technique can consist of adjustments to the vector lookup table entries. It is demonstrated that this method requires only a simple adaptation strategy because of the quadratic shape of the surface contour