Patent ID: 8824594

Claim:
A digital transmitter comprising: a digital upconverter generating a radio-frequency (RF) output signal having a predetermined output frequency from a sequence of predistorted digital in-phase (I) and quadrature (Q) data words generated from respective input I and Q data words provided from respective I and Q data channels; a programmable local oscillator (PLO) that provides a local oscillator (LO) signal to the digital upconverter in accordance with which the predetermined output frequency is established, the phase and period of the LO signal being selectable in accordance with a control signal provided to the PLO; and a predistortion processor receiving the input I and Q data words from the respective I and Q data channels and generating the predistorted I and Q data words, the predistortion processor comprising: an amplitude-modulation (AM) to AM (AMAM) predistortion processor that predistorts the I and Q data words in accordance with an AMAM distortion profile of the digital upconverter; and an AM to phase-modulation (AMPM) predistortion processor to provide the control signal to the PLO in accordance with the predistorted I and Q data words obtained from the AMAM predistortion processor, the control signal being indicative of a phase shift or period change in the LO signal at selected periods thereof in accordance with an AMPM predistortion profile of the digital upconverter, wherein the control signal is indicative of both the phase shift and the period change in the LO signal.