Use of sigma-delta modulation to control EMI from switch-mode powersupplies
Paramesh, J.; von Jouanne, A.
Industrial Electronics, IEEE Transactions on
Volume 48, Issue 1, Feb 2001 Page(s):111 - 117
Digital Object Identifier 10.1109/41.904570
Summary:Conducted electromagnetic interference (EMI) is a major cause of
concern in switch-mode power supplies (SMPSs) which commonly use
standard pulsewidth modulation (PWM). In this paper, sigma-delta
(ΣΔ) modulation is proposed as an alternative switching
technique to reduce conducted EMI from an SMPS. The result of using
ΣΔ modulation is a spread in the spectrum of the conducted
emissions so that large concentrations of power at discrete frequencies
are avoided. Experimental time-domain waveforms and spectra of the
switching function of first-order and second-order ΣΔ
modulators are presented to prove the viability of the scheme for EMI
mitigation. These modulators are then applied to a DC-DC converter in an
off-the-shelf computer power supply and experimental results show a
reduction of roughly 5-10 dB·μV in EMI emissions over standard
PWM modulators
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