A sub-mA phase-locked loop fabricated in a 65nm standard digital CMOS process is presented. The impact of process variation is largely removed by a novel open-loop calibration that is performed only during start-up but is opened during normal operation. This method reduces calibration time significantly compared with its closed-loop counterpart. The dual-loop PLL architecture is adopted to achieve a process-independent damping factor and pole-zero separation. A new phase frequency detector embedded with a level shifter is introduced. Careful power partitioning is explored to minimize the noise coupling. The proposed PLL achieves 3. lps RMS jitter running at 1.6GHz while consuming only 0.94mA.
对静态随机存储器(SRAM)全定制设计过程中的版图设计工作量大、重复性强的问题进行了分析,并在此基础上提出了一种新的应用于SRAM设计的快速综合技术。这种技术充分利用SRAM电路重复单元多的特点,在设计过程中尽可能把电路版图的硬件设计转换为使用软件来实现,节省了大量的版图设计和验证的时间,从而提高了工作效率。这种技术在龙芯Ⅱ号CPU的SRAM设计中得到了应用;芯片采用的是中芯国际0.18μm CM O S工艺。流片验证表明,该技术对于大容量的SRAM设计是较为准确而且有效的。
