Patent ID: 8229027

Claim:
A pre-distortion apparatus for a power amplifier, the pre-distortion apparatus receiving an input signal and an output signal of the power amplifier, and providing a pre-distorted output signal, the pre-distortion apparatus comprising: a memory delay block which provides a delayed signal that is representative of the input signal delayed by a predetermined amount; error signal generating circuit that generates an error signal that is representative of a difference between the output signal of the power amplifier and the delayed signal; and a pre-distortion circuit comprising: an envelope detector which generates an envelope signal that is representative of an envelope of the input signal; first and second polynomial function generating circuits responsive to the error signal, each polynomial function generating circuit receiving the envelope signal to provide in-phase and quadrature gain signals each representing a polynomial function of the envelope signal; a quadrature-phase shifter receiving the input signal to provide in-phase and quadrature representations of the input signal; first and second variable gain amplifiers receiving the in-phase and the quadrature representations of the input signal and the in-phase and quadrature gain signals to provide gain modulated in-phase and quadrature output signals; and a summer summing the gain modulated in-phase and quadrature output signals to provide the pre-distorted output signal.