请教论坛诸位高人关于D flip flop的问题

agenhcx 发表于 2013-1-4 13:02
谢谢回答！

setup,c-q, hold实际上是不是就是制约了clock的频率呢？

yes, but you still need to think about the propagation delay.

setup, c-q,hold must be treated very carefully because their values depends on the designs. For instance, it is possible to get a pulsed latches with setup time of 0 or even negative.

zheng18552 发表于 2013-1-6 02:56
Right now, at least according to my professor, the more important thing is the power issue not the ...

Thank you so much!

What kind of power are you talking about here? Dynamic or static? So higher frequency actually will cause higher more power consumption according to the equation. Is this your point?

zheng18552 发表于 2013-1-6 03:01
yes, but you still need to think about the propagation delay.

setup, c-q,hold must be treated v ...

Interesting, I looked it up, it is really helpful, thank you so much!

zheng18552 发表于 2013-1-6 02:55
1. About the race condition:
It is possible for one flip-flop to have a race condition. For instanc ...

Thank you for your reply!

I tried to look it up, but I still can not understand the meaning of CLK-CLK bar overlap. Would you please explain it more? Is it time overlap by two DFF because of skew?

agenhcx 发表于 2013-1-5 17:22
Thank you for your reply!

I tried to look it up, but I still can not understand the meaning of  ...

CLK is clock you used in your flip flop
CLK bar is clock bar signal, which is basically the CLK signal with negative amp.
when CLK is 1, CLK Bar is 0, when CLK is 0, CLK bar is 1.

now, in practice, one cannot get perfectly CLK and CLK Bar signal without any overlap.
Because of the overlap I mentioned, the race condition arises.

zheng18552 发表于 2013-1-6 07:31
CLK is clock you used in your flip flop
CLK bar is clock bar signal, which is basically the CLK s ...

Thank you so much!

几乎看不懂楼上几帖在谈什么，到底是互相秀半桶水的英语还是讨论学习啊？

对单个dff讲frequency没有任何意义，前面已经说了在dff做的pipeline里最大freq怎么算，没想到你们两个还能煞有其事搞一坨什么freq啊power啊什么的。
对单个dff讲power也没什么意义，dff不switch还要它干嘛啊，所以不用考虑很多static power。
dynamic power ～ f^2, 你说和freq关系大不大。要减小flops的power绝大多数情况下是加clock gating逻辑

liuzhe0320 发表于 2013-1-8 04:39
几乎看不懂楼上几帖在谈什么，到底是互相秀半桶水的英语还是讨论学习啊？

对单个dff讲frequency没有任何 ...

您老能回答问题我自然是感激不尽，动不动就喷人真是让人无语

不知道您是从哪里看出来在秀半桶水英语了，感情用英语讨论问题就变成秀英语了？人家zheng同学发帖的时候说不定在学校lab不能打中文，难道就不能打英文了？我看到的时候就在学校lab，没法打中文，而且鉴于人家说的是英文，我也打英文，不知道哪里惹着您老了。

再说我的英语肯定是半桶水，人家zheng同学的英语怎么说都不是半桶水。我倒是不知道您老的英语水平怎么样，反正我周围的情况是native的学生或者老师那基本都是不会嘲笑讽刺国际学生的口音和英语的，倒是那些中国人一天到晚在鄙视这鄙视那的，轮到自己说的时候倒是半天说不出一句话来。不知道是嫉妒还是有被害妄想症。

再说我和zheng同学用英语和讨论学习难道矛盾了么？就算我的英语垃圾，那我在日常生活中就不能用英语讨论问题了？我是不是上完课还要让美国教授发一份中文版的讲义？我是不是只能和中国同学讨论问题？如果TA是美国人我还不能问问题了是不是？

还是按照您老的意思我问问题之前要先去writing center或者哪里把我要问的全部polish一遍，直到没有任何语法错误，然后再去问？

而且您老看不懂我们讨论什么怎么就得出是半桶水英语了？怎么就不可能是您老自己半桶水英语呢？当然您说的没错，我肯定是半桶水英语，但是我倒是很怀疑您老的英语能比zheng同学厉害

当然您老要是说的是我，我全盘接受，我就是说的半桶水英语。如果zheng同学说他说的也是半桶水英语，我马上向您道歉。

liuzhe0320 发表于 2013-1-8 04:39
几乎看不懂楼上几帖在谈什么，到底是互相秀半桶水的英语还是讨论学习啊？

对单个dff讲frequency没有任何 ...

不过看完您的回复倒是更加坚定的让我认为您的英语貌似也一般，您最后一句话不就是zheng同学说的问题么

您要是工作不顺心想喷人请去mitbbs，您老要是想喷我，咱随时奉陪。

当然还是十分感谢您老回答问题

agenhcx 发表于 2013-1-7 21:15
不过看完您的回复倒是更加坚定的让我认为您的英语貌似也一般，您最后一句话不就是zheng同学说的问题么

...

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