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MaxDelay,MinDelay, max insertion

bharat kurra

 Hi All,

In my Clock.ctstch file i have mentioned

Maxdelay : 3.9ns

Min delay : 0ps

skew :150ps

after buliding clocktree i got an insertion delay of 1440 ps

Now i have changed Maxdelay to 900ps remaining same and again have run CTS still the insertion delay is almost the same

My question is for a given skew tool gives priority to which one Maxdelay or Min delay????

 

Thanx

Bharat Kurra

  • BobD

    You may want to try setting your max delay to 0ps.  The reason I say that is because CTS builds up the tree in stages and it's difficult to precisely target an overall insertion delay while each subtree is being built.

    Another thing to look at is your transition time requirements.  If they're very tight that can also increase insertion delay.

    Finally, if you're using 9.1 try "setOptMode -optLatency true".

    Reducing insertion delay is a first order way of reducing the effects of OCV, so many designers are interested in this subject.  If you get a chance to try these suggestions please do follow up and let us know how it goes!

    -Bob

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