SIGNAL PROCESSING APPARATUS

摘要

The predistortion circuit (200) predistorts the input signal to a non-linear signal processing device in order to linearise its output. The predistortion circuit (200) derives the predistortion by sampling the input at (210) and multiplies it with itself using mixers (multipliers) (220, 226, 230, 236, etc.) in order to generate various orders of distortion (212, 214, etc.) which are summed to provide the predistortion. Filter/time delay means (240, 242, 244) are incorporated in the paths which generate the orders of distortion in order to introduce a phase and/or amplitude variation with frequency into the distortion. The filter/time delay means can be implemented by adaptive filters in digital signal processing circuits (DSPs). The DSPs can sample the output of the signal processing device being linearised in order to obtain feedback for adapting the filter(s).