Patent ID: 7403573

Claim:
An uncorrelated adaptive predistorter configured for use with an RF power amplifier, the uncorrelated adaptive predistorter comprising: an input loop configured to be coupled to the input of an RF power amplifier, the input loop including a look-up table containing predistortion values derived from a spline function with knots wherein knots of the spline function are placed along an index of the look-up table, the input loop configured to apply the predistortion values to an input signal, in response to a monotonically increasing function of the input signal power, for forming a predistorted input signal; and an output loop coupled to the output of the RF power amplifier, the output loop including circuitry operable for selecting an intermodulation distortion product from the RF power amplifier output and including detector circuitry configured to measure the magnitude of the intermodulation distortion product of the RF power amplifier output resulting from the predistorted input signal; processing circuitry operable, upon variation of the placement of the knots along the look-up table index, to generate predistortion values and to evaluate the measured magnitudes of the respective intermodulation distortion products that result from the variation in knot placement and resulting predistortion values, the processing circuitry further operable to update the predistortion values in the look-up table based on the magnitude evaluation, so that the updated predistortion values in the look-up table are uncorrelated with respect to the input signal.