US Patent 8649471 Application of crest factor reduction to a signal

A technique for applying crest factor reduction to a signal involves identifying peaks of an oversampled digital signal that exceed a threshold and generating a correction waveform corresponding to a sequence of correction pulses for respective peaks. The correction waveform is applied to the oversampled digital signal via a delta-sigma modulator to generate an oversampled digital output signal with reduced peaks. The delta-sigma modulator causes most of the energy of the correction waveform in the oversampled digital output signal to fall outside a frequency band of the oversampled digital signal. The oversampled digital output signal is low pass filtered to remove energy outside the frequency band of the oversampled digital signal such that noise introduced into the oversampled digital output signal by the correction waveform is reduced. The oversampled digital output signal is down sampled to produce a digital output signal with a lower sampling rate.