For efficiency in terms of power consumed and power delivered, the PA 106 should be operated near its saturation point (PSAT). However, operating a PA near PSAT introduces nonlinear distortions at the output of the PA and degrades the bit error rate (BER) performance. To compensate for AM/AM and AM/PM distortion caused by the PA 106 when operated near PSAT, the I and Q signals are pre-distorted by the DPD component 108. The DPD component 108 includes a complex gain adjuster that controls the amplitude and phase of the input signal. The amount of predistortion is controlled by entries in a calibration lookup table that interpolate the AM/AM and AM/PM nonlinearities of the PA 106. Put another way, the amount of predistortion is controlled by correction values for the AM/AM and AM/PM nonlinearities of the PA 106 stored in the calibration lookup table. The level of the envelope of the input signal is used to index the calibration lookup table. The complex gain adjuster, given correction values from entries in the calibration lookup table, provides inverse nonlinear characteristics to that of the PA 106.

The correction values of the entries in the lookup table are determined by a calibration process performed using the auxiliary receiver circuitry 104 to characterize the PA 106. The calibration is performed when the radio 100 is powered on. The calibration may also be performed during operation of the radio 100, e.g., periodically to accommodate changes in characteristics of the PA 106 due to factors such as temperature change, voltage variations, channel changes, and aging.