A 3 GHz Spread Spectrum Clock Generator for SATA applications using chaotic PAM modulation

Abstract

This paper proposes a prototype of a spread spectrum clock generator which is the first known specifically meant for 3 GHz Serial ATA-II applications. The modulation is obtained from a fractional PLL which employs a Delta-Sigma modulator. A further innovative aspect of our work is that our prototype takes advantage of a chaotic PAM as driving signal, instead a triangular signal as in all spread spectrum generators proposed in literature for SATA-II. In this way we avoid the periodicity of the modulated clock, completely flattening the peaks in the power spectral density. The circuit prototype has been designed in 0.13 mum CMOS technology and achieves a peak reduction greater than 14 dB measured at RBW = 100 kHz. The chip active area is 0.27times0.78 mm2 and the power consumption is as low as 14.7 mW.