EMI Reduction by Spread-Spectrum Clocking in Digitally-Controlled DC-DC Converters

Ibuki MORI  Yoshihisa YAMADA  Santhos A. WIBOWO  Masashi KONO  Haruo KOBAYASHI  Yukihiro FUJIMURA  Nobukazu TAKAI  Toshio SUGIYAMA  Isao FUKAI  Norihisa ONISHI  Ichiro TAKEDA  Jun-ichi MATSUDA  

Publication
IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E92-A   No.4   pp.1004-1011
Publication Date: 2009/04/01
Online ISSN: 1745-1337
DOI: 10.1587/transfun.E92.A.1004
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Advanced Technologies Emerging Mainly from the 21st Workshop on Circuits and Systems in Karuizawa)
Category: 
Keyword: 
PWM control,  spread-spectrum clock modulation,  EMI,  digitally-controlled DC-DC converter,  

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Summary: 
This paper proposes spread-spectrum clock modulation algorithms for EMI reduction in digitally-controlled DC-DC converters. In switching regulators using PWM, switching noise and harmonic noise concentrated in a narrow spectrum around the switching frequency can cause severe EMI. Spread-spectrum clock modulation can be used to minimize EMI. In conventional switching regulators using analog control it is very difficult to realize complex spread-spectrum clocking, however this paper shows that it is relatively easy to implement spread-spectrum EMI-reduction using digital control. The proposed algorithm was verified using a power converter simulator (SCAT).