Adaptive complex gain predistorter for a transmitter

摘要

Symbols are transmitted in a Cartesian transmitter by pre-distorting an input signal X having in-phase and quadrature components using a first compensation lookup table operable to hold complex valued entries to carry out in-phase and quadrature compensation pre-distortion with respect to the input signal to form a pre-distorted signal Z. The pre-distorted signal Z is processed to form an output signal Y using a nonlinear element. A complex gain normalization parameter adaptively updated to reflect varying gain of a linear region of the nonlinear element. A normalized feed back signal {tilde over (Y)} is formed using the adaptively updated complex gain normalization parameter. The first compensation lookup table is updated based on the pre-distorted input signal Z and the adaptively normalized feedback signal {tilde over (Y)}.