Patent ID: 8081711
Filing Date: 2011-12-20
Classification: H03F,H04L

Abstract:
1. A method of predistorting signals in a polar modulation transmitter to counteract amplitude modulation to amplitude modulation (AM/AM) and amplitude modulation to phase modulation (AM/PM) distortion, comprising: scaling an envelope component signal according to an average power-level-dependent scale parameter selected from a plurality of average power-level-dependent scale parameters depending on which average power level of the plurality of different average power levels that a power amplifier (PA) is configured to operate; offsetting the scaled envelope component signal according to an average power-level-dependent offset parameter selected from a plurality of different average power-level-dependent offset parameters depending on which average power level of the plurality of different average power levels that the PA is configured to operate; predistorting the scaled envelope component signal in an amplitude path of the polar modulation transmitter according to a set of AM/AM predistortion coefficients of a predistortion look up table (LUT); after predistorting the scaled envelope component signal, further scaling the scaled envelope component signal according to second average power-level-dependent scale parameter selected from a plurality of the second average power-level-dependent scale parameters depending on which average power level of the plurality of different average power levels that the PA is configured to operate; after further scaling the scaled envelope component signal, offsetting the further scaled envelope component signal according to second average power-level-dependent offset parameter selected from a plurality of the second average power-level-dependent offset parameters depending on which average power level of the plurality of different average power levels that the PA is configured to operate, and predistorting a phase component signal in a phase path of the polar modulation transmitter according to a set of AM/PM predistortion coefficients of said predistortion LUT, wherein the sets of AM/AM and AM/PM predistortion coefficients of said predistortion LUT are shared over a plurality of different average power levels that the PA of polar modulation transmitter can be commanded to operate.