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Setup and Hold check in multicycle design!

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yadavvlsi

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In a multicycle path of two cycle set setup is checked at the second cycle and hold is check at first cycle. Why?
 

who said the hold check is always done in the 1st cycle when the setup check is done at the 2nd cycle ? You should learn a little bit how the logic circuit works.
 

It is always not so..I said that in multicycle path of 2( means It takes two cycles to complete the path). Hold is check one cycle before setup is checked in a multicycle path.. If it is n cycle path than setup is checked at nth cycle and hold is checked at (n-1)th cycle. Hold is always checked one cycle before setup is checked in a molticycle path.!
 

If you dont say anything in your timing constraint, the hold check is normally assumed one clock cycle before setup. Therefore, hold is checked at the n-1 clock edge if the path is n cycles long. You can specify when the hold check occurs in your multi-cycle constraint. Check the man page of your synthesizer.
 

It just depends on how you use the tool.
Some tools like magma have an option to configure the tool whether hold edge moves as the setup edge moves or not.
I think even Synopsys has the way not to move the hold edge when the setup edge moves. I forgot how, though.
 

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