Patent ID: 8170508
Filing Date: 2012-05-01
Classification: H03F

Abstract:
1. A method of determining coefficients of a pre-distorter for correction of distortion of a signal, the distortion being introduced by a radio frequency amplifier in a system comprising the pre-distorter, the amplifier, a first sampler for sampling the signal input to the amplifier, and a second sampler for sampling the signal when output from the amplifier, the method comprising: using the first sampler to sample the signal, whereby to generate a plurality of input samples; using the second sampler to sample a plurality of output samples, each of the plurality of output samples corresponding to one of the plurality of input samples; calculating a figure of merit for one or more of said plurality of input samples on the basis of a comparison of a first frequency spectrum with a second frequency spectrum, the first frequency spectrum being a frequency spectrum of a set of input samples comprising the one or more of said plurality of input samples and a previously selected set of input samples; selectively updating the previously selected set of input samples with said one or more of said plurality of input samples on the basis of the calculated figure of merit, whereby to generate an updated selected set; and determining the coefficients of the pre-distorter on the basis of at least some of the input samples in the updated selected set and the corresponding output samples.