An advanced spread-spectrum clock generator with triangular modulation for EMI suppressing

In this paper, an advanced spread-spectrum clock generator (SSCG) with triangular modulation is presented. It is more compact than general frequency jittering circuit. Furthermore, the circuit minimizes effect caused by leakage current. A theoretical analysis of the frequency modulation process and some considerations about the influence of the modulation parameters are also pointed out in this paper. The proposed SSCG can generate clocks of 132KHz with center spread ratios of 6.06%, 3.03%, 1.51% and 0.75%. The proposed circuit has been fabricated in a 0.5μm BCD process, and was applied to a fly-back switching converter. Experimental results confirm the theoretical analyses.