How to fix setup and hold violations?

[jaseel_abdulla]

Hi Seniors

Suppose in a design there are set up and hold violations.

which one should be fixed first and why.

Is fixing both is important. how can we fix them??

Please help me......Plz share your thoughts.


Thanks in advance

 

[avimit]

Re: Violation question!!

Fixing both are important. You may fix either one before the other. But just remember one thing a chip violating hold, is of no use, where as if there is a setup violation in a chip, then you may be able to make it work by reducing the freq of operation
Kr,
Avi
http://www.vlsiip.com

 

[jaseel_abdulla]

Re: Violation question!!

Thank you sir.

Can you tell me, how to fix hold time violation.

Other than reducing frequency, is there any method to avoid setup violation.

Thanks

 

[shavakmm]

Re: Violation question!!

All VLSI engineers scratch their head to eliminate setup and hold violation... different methods and optimization steps are there in different steps of VLSI IC design flow to counteract setup and hold violations.... please search within edaboard.com ...u can find several discussions.

https://asic-soc.blogspot.com

 

[au_sun]

Violation question!!

For fixing Hold violation between two registers,
various techniques are there,
1. try to add delays cells in between the registers without violation setup timing
2. try to utlize usefull skew in the clock paths betwwen two registers.
etc..

for Fixing setup,
1. try to optimize data path between two registers, without violation hold timing
2. try to fix the transition violation in the data path.
3. swapping low driving cells with high driving cells.
etc....

all the above techniques can be used based upon the suitable conditions, without creating further violations