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calculate max freq and hold

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jitendravlsi

jitendravlsi

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Dear All,

Please calculate the max frequency for the circuit attached here.

Will it work or not and why?

How much hold violation is there?

How to make it work this circuit?

THANX
JIT
 

Just go through the basics of STA, you can easily solve this.

If you want any help related to STA materials, any of us can help you.
 
hello friend,

this ckt will not work due to 100ps hold violation.

tsk+th </= tcomb + tc2q
(-200) + 500 < 100+100
300 < 200

so there is 100ps hold violation. here skew is -ve.

play with skew or increase your combo delay (not suggestable most of the times)
i prefer a better skew balancing

regards,
Sunil Budumuru
 

    jitendravlsi

    jitendravlsi

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thanks sunil,

even i gave the same answer...............


thanks
 
Dear Sunil


I tried to solve this question by playing with skew.
But I could not solve it.

Here setup slack is 0ps
hold slack is -100 ps
Clock cycle is 500 ps

I think we can only reduce the frequency of this circuit to make it work.

would you please try to put your views on this?

thanx jit
 

Hi Jitendra,

Increase the delay of the combo logic by 100ps.
Then we can make the circuit to work.

Pandit M
 

Dear Pandit,

Analyse the circuit carefully

just by increasing the combo delay by 100 ps you will get setup violation by 100 ps.

here only way to work this circuit is use 600 ps clock cycle means reduce the frequency of the circuit and then to increase the combo delay by 100 ps.


thanx
 

so jiten,
Its the same as pandit said,
The circuit can't operate at 500ps clock period as in the same condition, you dont have option to play with the skew to overcome hold as setup just met, so the best thing is to decrease the operating freq and increase the combo delay
 

    jitendravlsi

    jitendravlsi

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