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jerry2007
Joined: 26 Jun 2007
Posts: 9
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 06 Sep 2007 0:02 sdf questions |
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Hello everyone, my sdf looks like
(IOPATH A Z (0.195::0.202)(0.225::0.236))
how come only min/max are there but no typical value (verilog has all three)? is it then assumed as 0?
thanks in advance!
-Jerry
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sam536
Joined: 04 Jul 2007
Posts: 135
Helped: 14
Location: Tokyo
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| 06 Sep 2007 3:03 Re: sdf questions |
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SDF depends on the analysis type,whether your design uses a single operating condition or bc_wc/OCV operating conditions .
For single analysis type the SDF delay triplet has three identical values, for example instance, (15.0:15.0:15.0).
For BC_WC and OCV , the SDF triplet contains only two delays for the two different operating conditions, for example , (15.0::20.0).
In this case, the typical value of the SDF triplet is not used.
Regards,
Sam
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jerry2007
Joined: 26 Jun 2007
Posts: 9
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| 06 Sep 2007 20:15 Re: sdf questions |
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Thanks for the explanation, Sam.
I did set analysis mode to 'single' with only one library (with encounter), but I also used 'timingderate -early/late', maybe that changed the analysis mode to OCV? so with only one library (no max/mix lib), do i need to set timing derating factors?
what's strange is that back-annotation fails (setup viol) for both min/max and only passes for typ (seems to be actually 0 in this case). So I guess it's not that my backannotation is wrong but the backend design really has timing problems?
Thanks again!
-Jerry
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