list hold time violation and corresponding resolution

[ls000rhb]

Dear all, come on and talk about hold time issues.
Please share your experience when tackling the hold time violatons.and list them
when and why the hold time issues occurs, how to handle them?
I think it's valuable to converge our skillful methods here.

Thanks for every hot heart

BR.
ls000rhb

 

[firewire2035]

hold time will not be addressed until after CTS.

 

[jimaaa0]

when hold time violatons occur ,the token (data_in)will transmit trough the next FF or latch before they capture the data.

 

[iwpia50s]

Hold time should be addressed after CTS and detail routing. Fixing hold violations before the clock is routed is a waste of time...you will have to do it again.

 

[lakshman.ar]

Hold time occurs if this condition is violated

(Tcombo + tcq ) >> Thold.

If this condition is violated, it implies tht the combo delay is less than the hold time of the flop. So the data from the launch flop reaches faster to the D pin of the Capture flop ( evn b4 the clock can arrive), hence the data will be captured in the same clk cycle rather than the nxt one ... this is "hold" time violation !

fixing hold time viol :
1. Endpoint fixing : Putting a Buffer @the D pin of the "capture" flop
2. Start point fixing : Putting a Buffer @the D pin of the "launch" flop
3. intermediate fixing: trail and error method of Putting a Buffer in the combo logic to fix the violation

most violations get fixed by step 1 itself or else within step2 !!

Step 1 fixes of the hold viol for multiple start points which have one endpoint

Step 2 fixes of the hold viol for one starting point paths which have multiple endpoint