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Instantiating one of many layout views of a cell within itself

VenuA
VenuA over 9 years ago

I have searched all the forums before I typed this. This is a very interesting problem I am seeing. I really appreciate an answer from experts.

Say I have a cell named say "myCell" with "layout", "layout_iso" views. Along with symbol and schematic views. Schematic cell has instances with pPar("cdfParameter1") waiting to pass the parameter from any placement of symbol in a real test bench. 

Special Note: layout_iso uses layout view placement (not really recursive, but uses its same cell level view) 

Question here: is this right to use place a view of its own cell? Definitely not correct on the schematic side, I cant place them. but on the layout side is this right?

Say, I created a test schematic cell : testBench, with view schematic: with placement of myCell symbol with nets. I set the cdfParameter1 to whatever the value is allowed on.

I don't have a layout view for testBench, but if it were, the contents of the layout were exactly the same as myCell layout.

LVS correctly running Case:

Under the above assumption, I am running an LVS using : schematic view of testBench cell, layout view of myCell (because the geometries are the same)  ------> LVS is clean.

i.e. testBench->schematic vs myCell->layout LVS is CLEAN.

Error Case:

If I run LVS on testBench schematic vs layout_iso view (that contains a placement of layout view), LVS errors out saying, cdfParameter1 can not be evaluated on the myCell schematic instance. I am under the impression that this is because it could not pass or evaulate the cdfParameter from parent testBench cell. 

i.e. testBench->schematic vs myCell->layout_iso (using the placement of layout) LVS is ERRORS.

Error: *ERROR* Can not evaluate parameter value 'cdfParameter1' on inst 'M1' in cell 'myCell schematic myLib'
        cdfParameter1=0

Note: cdfParameter1 is pPar("cdfParameter1") on M1 instance.

cdfPamrameter1 is set as a radio button with string options in CDF of myCell. Also parseAsCELL is set to yes.

Please let me know why placement of it's own view on layout side  has reported an error on schematic side evaluation.

But when in correctly running case same parameter is passed correctly if the same schematic used, but layout is flat.

It would be really great if somebody can repsond on this.

Regards,
Venu

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