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set_output_delay in DC

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Wenf.Yeh

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set_output_delay

I'm get confused by the a command of DC-----set_output_delay
who can give me some suggestion about how to use it correctly and why ?
 

set_output_delay example

If a signal A_OUT is coming out of your block A, and is expected to go into another block B, and is expected to consume say tBns from the time it leaves block A and is consumed inside block B, by say some register, then your output delay value on the port A_OUT in the block A should be tBns.
Here I am assuming that block A and B are running off same clock.
Hope it helps,
kr,
Avi
http://www.vlsiip.com
 

    Wenf.Yeh

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set_output_delay + design compiler

thx Avi!
I know the delay where it come from.
uponds on ur example, I still have a question that why the inner delay on block B calculated into the output_delay on A_OUT of block A?
 

set_output_delay -min

Say logic inside the block B before being captured say require tb ns. Then your output delay for block A should be T-tb ns ,where T is clcok period. They synthesis tool try to optimize logic in block A to meeting your output timing delay requirement(T-Tb). Otherwisw the block B capture FF could not catch the data sent by blcok A. I hope you got it
 
dc set_output_delay

pls see attached gif file.Hope this illustration will help .
 
set_output_delay synopsys dc

Generally, the timing budget for output_delay is 60 % of clock cycle.


David
 

set_output_delay what is output delay

thx David!
I got it!

Arthur
 

output delay + synthesis dc

all the timings are calculated reg-reg. in a partitioned design, you may not have all the signals leaving from q-pin. same is the case with the flop in the next partition. to account for total delay between these to flops you need set_input_delay and set_output_delay
 

set_output_delay -reference_pin

I cannot download
 

dc set_output_delay

I know the delay where it come from.
uponds on ur example, I still have a question that why the inner delay on block B calculated into the output_delay on A_OUT of block A?
 

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