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Is Spread Spectrum Clocking Effective for EMI Reduction?

11 Dec 2015   10:00-11:00

Prof. Gianluca Setti
Abstract: A suitable modulation of the timing signal regulating the behavior of switching power converters and digital systems boards, know and spread spectrum clocking, has attracted significant attention in the last decade as a way to reduce the power density spectrum (PDS) peak of Electromagnetic Interference (EMI). Indeed, when a classical frequency modulation is used for this purpose, the shape of the spectrum in the neighborhood of each harmonic of the original timing signal can be proven to depend on the statistical features of the modulating signal. After reviewing the fundamental of the spread spectrum clocking method, in this talk we will first show that optimal reduction of the EMI theoretical spectrum can be achieved when the modulating signal is generated by a chaotic map for which the asymptotic probability density function of the generated samples is uniform, as it happens for the well-known Tent map or the Bernoulli shift. This is confirmed also by experimental results showing that, with such nonlinear-dynamics based methodologies a further reduction of more than 7dB in the power density spectrum peak is possible, with respect to other techniques based on the use, for spread spectrum clocking generation, of a triangular modulating signal (employed by several products of TI, Fujitsu, Philips and Maxim) or other known and patented ones (employed by Cypress).

209, Technická 2
Contact person
Norbert Herencsar
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