US Patent 8121560 Pre-distortion with enhanced convergence for linearization

A pre-distorter is provided for distorting an RF input signal to provide a pre-distorted radio frequency (RF) input signal to an amplifier that provides an amplified RF output signal, wherein the RF input signal has an envelope. The pre-distorter includes: a radio-frequency signal processing circuit that distorts the RF input signal according to a polynomial of powers of the envelope, each power of the envelope being weighted by a corresponding pre-distortion weight; and a performance monitor operable to compare a version of the amplified RF output signal to a delayed version of the RF input signal to provide an error signal, wherein the performance monitor is configured to iteratively adapt the coefficients based upon a gradient of a cost function, the cost function being a function of the error signal.