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sunil_ic
Joined: 22 May 2006
Posts: 10
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 04 Sep 2007 7:32 how setup time reduce? |
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Dear all,
I found that if we connect more flip flop in cascade then we can reduce the setup time. Is it true ? how ?
Thanks
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vamsi_addagada
Joined: 05 Jul 2007
Posts: 99
Helped: 3
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| 04 Sep 2007 8:07 how setup time reduce? |
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hi sunil
no yaar .first u r increase the time period and decrease the delay of data path
Added after 2 minutes:
vamsi
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s_prasan
Joined: 08 Dec 2006
Posts: 4
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| 04 Sep 2007 9:01 Re: how setup time reduce? |
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Hi Sunil,
Normally when we see a very long data path betn flops, the setup tends to violate. One of teh ways to fix it is to break the data path into two by inserting a flop in between. Thus, it appears as a cascade!!!
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ameed
Joined: 28 Jun 2007
Posts: 119
Helped: 5
Location: INDIA
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| 04 Sep 2007 12:56 Re: how setup time reduce? |
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hi,
possible only with parallel processing.
thanx......
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sunil_ic
Joined: 22 May 2006
Posts: 10
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| 04 Sep 2007 13:16 Re: how setup time reduce? |
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Dear,
You misunderstood my question. Actually I have a flip flop of standard cell library. Now its setup time is fixed. Recently in one interview I was asked how can we reduce that setup time. And the answer was, if we connect the flip flops in cascade we can reduce the setup time with out touching the combinational logic. But I am confused how can it happen ? Say we have two flip flop having 1ns setup time and in between those flops we have combinational logic having 150ns propagation delay. now clock is running such that setup time violation occuring. So without touching the combinational logic and clock, how can we to reduce the setup time of the second flipflop to 0.5ns ?
Thanks
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amitjagtap
Joined: 10 Jan 2007
Posts: 89
Helped: 3
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| 05 Sep 2007 10:55 how setup time reduce? |
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hi sunil
I read ur question.
we can not change the minimum setup time req of 2nd ff.
I think setup time violation for 2nd FF can be avoided by putting a buffer in clock path of 2nd FF.So that clk edge will come late(buffer delay) at 2nd FF,where as data is present at usual time.
I'm not getting the concept of cascading of FF.
thanks, eager to hear from u.
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sunil_ic
Joined: 22 May 2006
Posts: 10
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| 06 Sep 2007 17:54 Re: how setup time reduce? |
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| I also eager to know the reason.
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