A Clock Generator with Dual Pseudo Random Spread Spectrum in DC-DC Buck Converter

In this paper, a spread-spectrum clock generator used in buck converter to realize low electromagnetic interference (EMI) is presented. To make the switching frequency further modulated randomly, dual random spread spectrum effect is implemented by changing the arrays of both current and resistor. The compact circuit achieves $6 \%$ spread of the switching frequency. A DC-DC buck converter with the proposed scheme is designed and fabricated in a $0.18-\mu \mathrm{m} \mathrm{BCD}$ process for verification. The peak power spectrum is reduced by 15.4 dB with $V_{I N}=12 \mathrm{~V}$ and $V_{\text {out }}=3.6 \mathrm{~V}$.