我在做一个输入1200MHz的PLL,本来对于如此高的输入频率，我的办法是前置一个div2 or div4，但是系统有一个硬指标，带宽与输入频率比为1/20，如果div2 or div4以后，就很难在各个corner满足这个指标。1200MHz的 PFD很难做，charge pump就更难了，不知道各位有没有办法，谢谢。
另外如果用DPLL的话，jitter的要求可能是个大问题。
If the same signal were tested with a shorter ruler, say, 0.25 unit intervals long, then the ruler would certainly be crossed less frequently. Perhaps only one waveform out of every 100,000
waveforms, on average, would cross this shorter ruler. One could say that, aside from one waveform in 10 , the eye was 25% open.
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发表于 2013-4-12 12:17:47
