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Other CAD Tools >> Physical Verification, Extraction and Analysis >> How to do double guard ring without problem of diodenwx?
https://designers-guide.org/forum/YaBB.pl?num=1404572396

Message started by Jacki on Jul 5^th, 2014, 7:59am

Title: How to do double guard ring without problem of diodenwx?
Post by Jacki on Jul 5^th, 2014, 7:59am

Hi All,

I am adding a double-guard-ring for NMOS in the layout (inner ring is P-ring, outer ring is N-ring), but in DRC check, it seems I have the problem of diodenwx. The error is "DIODENWX not over DIODE" must be connected in parallel to a similar diode in a device which is compared in LVS. Then I add the tie-down diode n-diffusion in substrate, but still the problem cannot be solved.
First I want to understand why I get this DRC error, because I think I follow the normal double-ring rule to add the double ring for the NMOS transistors.
Second, even I need to add a similar diode in parallel, I think the tie-down diode between n-diffusion and p-substrate should be the right one in the layout, why it doesn't work?
Any comments are appreciated.