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global net connections for VSS are missing after the save

anil chatrathi over 10 years ago

Hi All,

I have design, where FP is done and global net connection rules are created and saved the database.

If I load the database the connections are missing for only for VSS in all std cells giving the below errors:

**ERROR: (ENCDB-1220): A global net connection(GNC) rule for connecting pin 'VSS' of cell 'AND' to global net 'VSS' was specified. The connection cannot be made because the ground pin and the power net are not of the same polarity. Check the imported design and make sure the GNC rule is correctly specified or generated.

I tried reconnecting the global nets but give the same error above.

Please help me if any one face this kind of issue.

Regards,

Anil

Kari over 10 years ago

Make sure that the VSS pin and VSS net are both USE GROUND (not POWER). In the .globals file when loading the design, make sure VSS is listed in the gnd nets variable and not the pwr nets variable.
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anil chatrathi over 10 years ago

Thanks, kari. Actually these nets ( VDD and VSS) are defined in the input netlist with out giving any atrributes. This is creating the isse.
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Kari over 10 years ago

It is not typical for VDD/VSS to be in the netlist. EDI probably thinks they are signal nets in this case. VDD/VSS should have direction INOUT and are usually handled with globalNetConnect statements.
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anil chatrathi over 10 years ago

what is the use of keeping VDD VSS nets in the netlist? some how removing them in the netlist and using globalNetConnect worked for me. But if I keep the them the same issue exists.
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Kari over 10 years ago

like I said, they are not normally in the netlist. I would question the source of the netlist, why they are there.
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