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Why we are not checking the hold before CTS?

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 Why we are not checking the hold before CTS?
Ans: Before CTS, clock is ideal that means exact skew is not there. All the clocks reaching the flops at the same 
Time. So, we dont have skew and transition numbers of the clock path, but this information is sufficient to 
perform setup analysis since setup violation depends on the data path delay. Clock is propagted only after CTS 
(actual clock tree is built, clock buffers are added & clock tree hierarchy, clock skew, insertion delay comes into 
picture) and that's why hold violations are fixed only after CTS.

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