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  3. Dummy back annotation problem

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Dummy back annotation problem

MMueller
MMueller over 8 years ago

Hi,

I did the following:

I used the Layout XL "Generate all from source" feature to generate a layout from my schematic. The schematic i used, though did contain instances which did not have layout cells. Therefore all these instances got "flattened" in the generated layout. This was intended and the idea was to use modgens to cope with all the flattened cells and their devices in the generated layout. So far everything worked fine... XL binding established etc...

The problem i have now is that when i try to back annotate the dummies i used in the modgens i get messages like:

*WARNING* (LX-3101): Cannot create instance terminal for terminal 'S' on schematic instance 'ModgenDummy_0_75_Modgen_3' because the schematic net 'UNIT_CELL_2X_1_I/net012' does not exist in cellview 'IDAC/schematic'.

Which results in dummy instances being generated in the schematic but without net connections. This makes perfectly sense because in the schematic the original hierarchy still exists  (and the nets are in different hierarchy ) whereas in the layout the cells got flattened. Up to this point it seemed that Layout XL could keep track of this non the less...

My question is now, if there is a solution to this problem or if it was a bad idea in the beginning to have "Generate all from source" "flatten" the cells in the layout....

I thought about flattening the schematic the as well (how could i do this?), back annotate dummies and do LVS...

Any suggestions?

Thanks and best regards,

Markus

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