Patent ID: 9093958
Filing Date: 2015-07-28
Classification: H03F,H04L

Abstract:
1. A predistortion circuit for providing distortion correction in a presence of harmonics, the predistortion circuit comprising: an input for receiving a digital input signal; an output for providing a digital output signal to an up-conversion element that produces harmonic terms comprising a plurality of different frequencies, wherein the up-conversion element is operably coupled to a non-linear device, and the digital output signal is a predistorted version of the digital input signal; a processor operably coupled to an output of the non-linear device for receiving an output radio frequency signal therefrom and arranged to determine a digital correction to be applied to the digital input signal; wherein the processor is further arranged to: determine the digital correction that comprises a plurality of in-phase and quadrature cross-terms of the digital input signal containing products of in-phase and quadrature terms, where terms of a same order have different co-efficients, wherein the digital output signal carries predistorted samples, and the predistorted samples are generated based on the plurality of in-phase and quadrature cross-terms; wherein the digital correction is generated from a row vector of N cross terms (Y where: Y wherein N is a positive integer that is greater than one; and the plurality of different co-efficients to be applied to each odd order harmonic term comprises a symmetrical relationship between the in-phase correction co-efficient and the quadrature correction co-efficient.