关于时钟

wilson

请问以下这段话到底是什么意思.我都看晕了.尤其是这句"and only 20 percent of the clock’s data path toggles in each cycle."是何意思啊.谢谢了.
Selecting the ‘pre-’ or ‘post-CTS’ clock options will performPower Analysis on each clock domain differently. The ‘post-CTS’ feature runs Power Analysis with clock nets at a clock rate (in MHz) for each clock domain, and the toggle probability (in percent) for the clock’s data paths. So, all the nets on the clock path toggle at the clock rate and only a percentage of the clock’s data path toggle in each clock cycle. For example, if the clock rate is 300 MHz and the Net Toggle Probability value is 0.2 (20%), then the clock path nets toggles at 300 MHz, and only 20 percent of the clock’s data path toggles in each cycle. The ‘pre-CTS’ feature is similar to post-CTS, except the clock nets do not toggle.Nets not belonging to a clock domain do not toggle.

iamchine

这正是某个工具关于功耗估算的说明。Pre-CTS是指时钟不工作时该时钟域的功耗分析，可以称作静态功耗分析；Post-CTS是指有时钟工作时该时钟域的功耗分析，可称作动态功耗分析。
至于那个百分比，就是说实际翻转触发器的个数占总触发器的百分比，才好计算功耗。

bravelu

问题是如何来估算这个百分比？在不同情况下这个比例应该是不同的，和具体逻辑有关。

iamchine

这个百分比就是由你的测试向量来得到了。