Patent ID: 6882221

Claim:
Apparatus for predistorting an input signal applied to a radio frequency (RF) power amplifier, the apparatus comprising: an RF phase discriminator, for generating output signals indicative of phase and amplitude differences between two input signals; means for coupling a portion of an RF amplifier input as a first input signal to the RF phase discriminator; means for coupling a portion of an RF amplifier output as a second input signal to the RF phase discriminator, wherein the coupled portion of the RF amplifier output is scaled to be comparable with the RF amplifier input; an analog-to-digital converter for converting difference signals generated by the RF phase discriminator to digital form; a computation module for deriving from the difference signals corresponding values of gain compression and RF amplifier output phase; means for coupling a portion of the RF amplifier input to the analog-to-digital converter, to derive RF amplifier input values in digital form; a digital memory, for storing in association with each other, values of RF amplifier input, gain compression and RF amplifier output phase; and an amplifier predistorter, for adjusting the amplitude and phase of the RF amplifier input based on the stored values of gain compression and RF amplifier output phase, to compensate for distortion in the RF amplifier.