说明：  对于系统设计工程师来说，时序问题在设计中是至关重要的，尤其是随着时钟频率的提高，留给数据传输的有效读写窗口越来越小，要想在很短的时间限制里，让数据信号从驱动端完整地传送到接收端，就必须进行精确的时序计算和分析。同时，时序和信号完整性也是密不可分的，良好的信号质量是确保稳定的时序的关键
(System Design Engineer for example, timing issues in the design is critical, especially with the clock frequency improve, leaving an effective reading and writing data transfer window is getting smaller and smaller, if in a very short time limit in so that data signals from the driver side completely transmitted to the receiving end, it is necessary to carry out precise timing calculation and analysis. At the same time, timing and signal integrity is inseparable, good signal quality is to ensure that the key to the stability of timing)