Predistorted Pulse Width Modulation Technique for Switching Signal Spectrum Management

Predistortion pulse-width modulation is proposed in this paper as a way to shape the spectrum of a switching signal. The key idea is to introduce a predistortion signal to the standard reference signal prior to a conventional triangle-comparison pulse-width modulator. A multicarrier and multisignal approach is employed to prevent low-frequency distortion in the switching signal. The approach can be used for spectral spreading of switching waveforms, for harmonic elimination, and for other applications. It avoids the distortion inherent in random switching methods. The method is much less computationally intensive than conventional harmonic elimination but adds flexibility. Experiments confirm the expected spectral performance.