A Spread-Spectrum Clock Generator Using Fractional-N PLL Controlled Delta-Sigma Modulator for Serial-ATA III

In this paper, a 6GHz spread-spectrum clock generator (SSCG) for Serial AT Attachment Generations 3 (SATA-III) is presented. By utilizing frequency modulation which employs digital MASH delta-sigma modulator and 33KHz triangular profile address generator, the SSCG achieves an output clock of 6GHz and 5000ppm down spread with a triangular waveform. The SSCG was designed based on TSMC 0.13μm 1p8m CMOS process. The power dissipation is 48mW under a 1.2V supply voltage. The peak-to-peak jitter of non spread-spectrum clock is 8ps, and the EMI reduction is 15dB with normal frequency spread modulation from 6GHz to 5.97GHz.

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