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Altera_Forum's avatar
Altera_Forum
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16 years ago

Timequest GUI

Hi,

my question considers the TimeQuest time analysis. Can someone explain me why does the Data Arrival/Required waveline changes after the latch clock ? From what I know it shall change before Latch time and stay stable during Tsetup time...

best regards

Joel

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    From your latch clock, there is a clock delay, pessimisim, uncertainty, etc. that changes when the actual latch clock hits the latching register. That being said, the data does arrive after this, and the slack is negative. So you're right, this is incorrect and it's basically telling you that this path failed timing. It should be in red, and negative slacks mean they failed timing.

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor

    I understand it now. What I missed was the bottom Clock Delay which is shown in respect to the Latch Clock. And the Clock Delay on the top is shown in respect to the Launch Clock. Its all clear now. Thank you.