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

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 EMIreduction using digital control. The proposed algorithm was verified using a power converter simulator (SCAT). key words: PWM control, spread-spectrum clock modulation, EMI, digitally-controlled DC-DC converter