A Wideband Programmable Spread-Spectrum Clock Generator

In this work, a spread-spectrum clock generator (SSCG) with triangular modulation is presented. The SSCG can be applied to most of microprocessor system. It has the effect of spreading the energy of a frequency harmonics over a wider bandwidth, and hence reducing the amplitudes of the harmonics. The digitally programming schemes are implemented in the charge pump current, the voltage controlled oscillator gain, the low-pass filter and the divider, to realize reusable silicon IP. The proposed SSCG can generate clocks of 64MHz-1920MHz with center spread modulation from plusmn1-MHz to plusmn50-MHz and the spread ratios equal to spread modulation divides output frequency. A test fabricated in a 0.18-mum CMOS single-poly six-metal process is fabricated. The area 1.01times1.14mm² including the loop filter. It consumes 100 mW of power at 266-MHz. Attenuation as high as 17dB is presented