[SOLVED] how does a flipflop with setup time violation function??

[mailsrikanth007]

flip flop setup time

Can someone tell me how a flipflop with setup time violation function? a flop with hold time violation will act as a simple buffer. In the same way how it acts with setup time violation?

Please let me know

 

[dcreddy1980]

setup time for flip flop

Increase the clock period, so that the logic will have enough time for the computation. Fro ex : if your clock period is "X ns" when u have seen a setup violation of "Y ns". Make u r new clock period to be "X+Y ns". This is the simplest way if you have relaxed target frequency.

 

[yx.yang]

flip flop setup time hold frequency

I don't think a flip-flop with hold violation is a buffer. In fact, the behavior of a flip-flop with setup/hold violation is unknow, the output value is unpredictable. And the CK->Q delay will increase.

 

[viju]

why hold time in flip flop

Hi mailsrikanth007,
Can you please quote the reference from where you find that "a flop with hold time violation will act as a simple buffer" ?
It is interesting to know about it...

I'm agree with yx.yang that "the behavior of a flip-flop with setup/hold violation is unknow, the output value is unpredictable. And the CK->Q delay will increase."

 

[mailsrikanth007]

function of flip flop delay

I dont have a reference but i can explain this way...

In a scan chain if one the flip-flop has hold time violaion then the output will appear one clock in advance. This is because the defected flip-flop cannot hold the value and acts as a buffer. This is how flip-flops with hold time violation are detected. I cannot give any reference for this but I am 100% confident because i was asked this question in one of the interviews and the interviewer himself gave me this answer.

In the same way I suppose there will be a way in which set-up time violation will affect a scan chain.

 

[RBB]

setup time in flip flop

Depending on the flip-flop architecture, a setup or hold time violation could cause the output of the flop be become unknown, or metastable

 

[pmat]

d flip flop setup time violation

I agree with the guys which state that it will move to a metastable state... The buffer-answer is poorly supported and as no reference was presented, i would suggest to leave it behind...

Pavlos