Patent ID: 7545880

Claim:
A wireless transmitter comprising: power amplifier circuitry having an AM to AM distortion characteristic for an input value range and adapted to amplify a pre-distorted transmit signal prior to transmission; and pre-distortion circuitry comprising amplitude pre-distortion circuitry adapted to: distort an amplitude component of a polar transmit signal based on a set of coefficients defining a polynomial describing an amplitude compensation signal that essentially cancels the AM to AM distortion of the power amplifier circuitry, thereby providing a pre-distorted amplitude component of the pre-distorted transmit signal; select the set of coefficients from a plurality of sets of coefficients defining a corresponding plurality of polynomials describing the amplitude compensation signal for each of at least two subsets of the input value range for each of at least two power levels of the power amplifier circuitry; and add the amplitude component of the polar transmit signal and the amplitude compensation signal, thereby distorting the amplitude component to provide the pre-distorted amplitude component of the pre-distorted transmit signal, such that the sum of the amplitude component and the amplitude compensation signal is essentially equivalent to a product of the amplitude component and a correction factor wherein the correction factor is essentially a multiplicative inverse of the AM to AM distortion of the power amplifier circuitry.