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扩频时钟产生器可以分散频率谐波的能量、减小单位带宽内的辐射能量,因此,扩频时钟产生器广泛应用在SATA Ⅲ等系统中。给出了一种基于失调锁相环技术的SATA Ⅲ扩频时钟产生器的设计方法。在扩频时钟产生器中,一个低频扩频信号和一个直接数字频率合成器进行频率合成,然后和一个高频信号混频,产生一个更高的调制参考源。扩频时钟产生器采用1.2 V 0.13μm CMOS工艺,功耗为21.16 m W,主要的频率功率减小了16 d B,芯片面积0.7*0.45 mm2。测试结果表明,采用失调锁相环技术,扩频时钟产生器具有较低的时钟抖动,较小的EMI辐射功率,较好地满足了SATA Ⅲ的需求。
Spread spectrum clock generator can disperse the energy of frequency harmonics and reduce the radiation energy in unit bandwidth. Therefore, spread spectrum clock generator is widely used in SATA III system. A design method of SATA Ⅲ spread-spectrum clock generator based on offset phase-locked loop technology is given. In spread-spectrum clock generators, a low-frequency spread spectrum signal is frequency-synthesized with a direct digital frequency synthesizer and then mixed with a high-frequency signal to produce a higher modulation reference source. Spread-spectrum clock generator using 1.2 V 0.13μm CMOS technology, power consumption of 21.16 mW, the main frequency power reduced by 16 d B, the chip area of 0.7 * 0.45 mm2. The test results show that the spread spectrum clock generator has a lower clock jitter and a smaller EMI radiation power, which better meets the requirements of the SATA III.