A novel spread-spectrum clock generator for suppressing conducted EMI in switching power supply

In this paper, a novel spread spectrum clock generator (SSCG) which spreads spectrum with variable current is presented. The proposed SSCG circuit not only occupies a small area but also minimizes effect caused by leakage current. The proposed SSCG circuit has been fabricated in a 0.5 μm BCD process and applied to a fly-back converter. The effectiveness of the proposed SSCG circuit in terms of peak EMI reduction is demonstrated theoretically and confirmed with experimental results.