Reduction in spectral peaks of DC-DC converters using chaos-modulated clock

Abstract

Electronic power converters are notorious sources of electromagnetic interference, and suppression of EMI is a major issue in switched-mode power converter design. A substantial part of the manufacturing cost of power converters for critical applications involves designing filters to conform to the varying EMI norms for the various domains, such as defence, aerospace etc. We propose a method of EMI reduction using spectral modification through chaotic modulation. The converter is operated in a regular periodic regime, and then the timing signal (the clock or the ramp waveform) is modulated with a chaotic signal. We have designed and fabricated a chaos-modulated clock circuit that can be easily implemented in CMOS. We have shown, by both simulation and experiment, that this results in a reduction of spectral peaks and a consequent spreading of the spectrum - which can be precisely controlled by adjusting the gain of the chaotic waveform. This scheme can thus eliminate filters and screens, or can at least reduce their size significantly.