Patent ID: 6304140
Filing Date: 2001-10-16
Classification: H03F

Abstract:
A method for predistorting a digital signal prior to amplification comprising:computing a look-up table using power values of digital input signal samples as look-up values wherein the look-up table is a function of pre-measured calibration data; wherein the step of computing comprises:determining a set of input power values;obtaining the pre-measured calibration data including an output power data value and phase data value of the amplifier corresponding to each of the input power values;deriving a set of calibration power values using the output power data values;deriving amplitude predistortion calibration values using the calibration power values and the input power values;determining phase predistortion calibration values from the phase data values;interpolating the calibration power values and corresponding amplitude predistortion calibration values to provide amplitude predistortion values;interpolating the calibration power values and corresponding phase predistortion calibration values to provide phase predistortion values; andwherein the look-up table is computed from the amplitude predistortion values and the phase predistortion values; andapplying the look-up table to digital input signals for producing the predistorted signal; wherein,the amplitude predistortion values and the phase predistortion values are polar values, the method further comprising:translating the amplitude predistortion values and the phase predistortion values from polar values to Cartesian values.