Patent ID: 7359683

Claim:
Apparatus for use in a wireless transmitter, the apparatus comprising: an amplifier for amplifying a radio frequency (RF) signal to provide an RF output signal for transmission; and a predistorter for injecting a distortion signal into the RF signal prior to amplification for use in linearizing the amplifier; wherein the predistorter includes a phase shifter operating at less than twice a carrier frequency of the RF signal and further including a signal path for conveying a clock signal having a frequency less than twice a carrier frequency of the RF signal and wherein the predistorter is in the signal path of the clock signal; wherein the phase shifter adjusts a phase of the clock signal and provides a phase-shifted clock signal, and wherein the predistorter further comprises: a mixer responsive to the phase-shifted clock signal and an intermediate frequency (IF) signal for providing the distortion signal; an amplitude adjuster coupled to the mixer for adjusting an amplitude of the distortion signal before application to the amplifier; a directional coupler disposed between the amplitude adjuster and the amplifier for injecting the distortion signal into the RE signal; and a processor for controlling the phase shifter and amplitude adjuster such that the distortion signal linearizes the amplifier.