A spread-spectrum clock generator with triangular modulation

A spread-spectrum clock generator (SSCG) with triangular modulation is presented. Only a divider and a programmable charge pump are added into a conventional clock generator to accomplish the spread-spectrum function. The proposed circuit has been fabricated in a 0.35-μm CMOS single-poly quadruple-metal process. The proposed SSCG can generate clocks of 66, 133, and 266 MHz with center spread ratios of 0.5%, 1%, 1.5%, 2%, and 2.5%. Experimental results confirm the theoretical analyses.