Patent ID: 8314656
Filing Date: 2012-11-20
Classification: H03F

Abstract:
1. A power series digital predistorter comprising: a linear transmission path delaying and transmitting an input signal; a distortion generating path comprising an Nth-order distortion generator generating an Nth-order distortion component of the input signal and an Nth-order vector adjuster adjusting the phase and amplitude of the Nth-order distortion component, where N being an odd number greater than or equal to 3, the distortion generating path outputting an output of the Nth-order vector adjuster as a distortion compensation component; a combiner combining the input signal output from the linear transmission path with the distortion compensation component output from the distortion generating path; a monitor measuring a distortion component of each of predetermined frequency bands contained in an output of a power amplifier amplifying the power of an output of the combiner; and a controller calculating an amount of adjustment of the phase of an Nth-order distortion component and an amount of adjustment of the amplitude of the Nth-order distortion component and setting the calculated amounts of adjustment in the Nth-order vector adjuster, the amounts of adjustment being used for generating the distortion compensation component cancelling the distortion component contained in the output of the power amplifier measured by the monitor; wherein the controller comprises: a vector adjuster control part which sets in the Nth-order vector adjuster a plurality of phase values and a plurality of amplitude values which are used for measuring a distortion component, finds dependence of a distortion component contained in an output of the power amplifier on a phase value set in the Nth-order vector adjuster and on an amplitude value set in the Nth-order vector adjustor from a plurality of distortion component measurements each obtained by the monitor under each of the plurality of set phase values and from a plurality of distortion component measurements each obtained under each of the plurality of set amplitude values, calculates a phase value and an amplitude value that cancel the distortion component contained in the output of the power amplifier from the found dependences, and sets the calculated phase value and amplitude value in the Nth-order vector adjuster; and a vector adjuster coefficient deriving part which, when the vector adjuster control part finds dependence of a distortion component contained in an output of the power amplifier on a phase value set in the Nth-order vector adjuster and on an amplitude value set in the Nth-order vector adjuster, derives a plurality of phase values and a plurality of amplitude values used for measuring the distortion component contained in the output of the power amplifier from previously found dependence of the distortion component on a phase value and on an amplitude value, respectively, set in the Nth-order vector adjuster, and provides the plurality of phase values and the plurality of amplitude values to the vector adjuster control part.