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antenna violations not being caught by SocEncounter

I have no process antenna violation in SocEncounter but when i import the design into Virtuoso for final DRC and LVS check, i get 10 antenna violations. From SourceLink , i found similar problem statement with solution stating that the ANTENNADIFFAREARATIO in LEF is not correctly set. These values for metal 1 in my case are

AntennaSideAreaRatio 396 ;
AntennaDiffSideAreaRatio PWL ( ( 0 396 ) ( 0.2267 396 ) ( 0.2268 9999999 ) ( 1 9999999 ) ) ;

Pls comment on how to determine whether these values are correctly set or not. Has anyone come across similar problems?

I even looked at the antenna report from the design. The portion of it looks like below

[1]      MET1: Area:    0.26 S.Area:    1.16 G.Area:    0.18 D.Area:    0.00
                Fact:    1.00     PAR:    1.42   Ratio:    0.00       (Area)
                Fact:    1.00     PAR:    6.42   Ratio: 396.00       (S.Area)
                                  CAR:    1.42   Ratio:    0.00       (C.Area)
                                  CAR:    6.42   Ratio:    0.00       (C.S.Area)

From encounter documentation, "Ratio" means target antenna ratio. How does encounter check antenna violation? Does it give violations if PAR > Ratio ?   I would appreciate your comments. Thanks.

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Kari over 16 years ago

Modeling the antenna characteristics in the LEF can sometimes be tricky. In all my years of doing chips, I have only seen one process where the LEF rules matched the DRC deck exactly. So, it's not uncommon for Nanoroute/FE to report that you are antenna clean, but still see a handful of violations when you run your signoff DRC deck. Having said that, most of the time you can model the antennas very closely if you spend some time on it. In the LEF/DEF Reference manual, Appendix C has a good chapter all about antenna calculations:
http://sourcelink.cadence.com/docs/files/Release_Info/Docs/lefdefref/lefdefref5.7/PAE.html#1033512
See if that information helps.
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Kari over 16 years ago

Modeling the antenna characteristics in the LEF can sometimes be tricky. In all my years of doing chips, I have only seen one process where the LEF rules matched the DRC deck exactly. So, it's not uncommon for Nanoroute/FE to report that you are antenna clean, but still see a handful of violations when you run your signoff DRC deck. Having said that, most of the time you can model the antennas very closely if you spend some time on it. In the LEF/DEF Reference manual, Appendix C has a good chapter all about antenna calculations:
http://sourcelink.cadence.com/docs/files/Release_Info/Docs/lefdefref/lefdefref5.7/PAE.html#1033512
See if that information helps.
Cancel
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