Missing layer in pCell

Hi there,

i'm missing a layout layer that should be present in a pCell when a
given button is selected (turning on an option) on the pCell.

So in device "nmos" there is "full_drc" button that increases the size
of the mos (making it more robust) but it should also draw a CAD layer
called "extra_rules" over the body of the device that will tell the
DRC deck to enforce more stringent checks on this cell. However, the
cell does increase in size when this button is turned on BUT the
"extra_rules" layer does not appear.

I've had a look in my CDS.log and there are no warnings or errors to
give me a clue. Does anyone have any suggestions how i might trace the
failure of this layer to be drawn? The layer "extra_rules" can be
drawn as a polygon so its does exist.

We are using cadence: IC5141_USR6

Thanks

Stu

 

[Andrew Beckett]

stuart.duncan@gigle.biz wrote, on 03/24/09 11:27:

Hi there,

i'm missing a layout layer that should be present in a pCell when a
given button is selected (turning on an option) on the pCell.

So in device "nmos" there is "full_drc" button that increases the size
of the mos (making it more robust) but it should also draw a CAD layer
called "extra_rules" over the body of the device that will tell the
DRC deck to enforce more stringent checks on this cell. However, the
cell does increase in size when this button is turned on BUT the
"extra_rules" layer does not appear.

I've had a look in my CDS.log and there are no warnings or errors to
give me a clue. Does anyone have any suggestions how i might trace the
failure of this layer to be drawn? The layer "extra_rules" can be
drawn as a polygon so its does exist.

We are using cadence: IC5141_USR6

Thanks

Stu

Stuart,

Is the layer a visible layer (i.e. is it turned on for display in the LSW)

You could look to see what shapes are in the pcell master - with the instance
selected, do:

car(geGetSelSet())~>master~>shapes~>layerName

and see if it's listed.

Or contact customer support - that's what we're here for!

Regards,

Andrew.

 

Hi Andrew,

Yes, the layer is in the LSW and visible. When i do:

car(geGetSelSet())~>master~>shapes~>layerName

The layer in question is NOT listed. I'm in touch with cadence
customer support so hopefully we can get to the bottom of this.
Its a strange issue as the pdk vendor say that they do see this layer
in a similar test case. I've logged a ticket with Cadence support.

Thanks

Stu

 

Hi Andrew, forgot to add that if you wish to e-mail me privately i can
give you the ref' of the cadence ticket and therefore PDK vendor info.

It's further complicated in that around 3 months ago i lay'd out a
some of these transistors and the the offending layer was apparent,
but now if i copy the same schematic and re-generate it, this layer
has gone from the pCells. Unfortunately in that time we have changed a
cadence version and probablly a few other environment settings (new
kit and new project) so its difficult to nail down exactly when this
change took place.

Thanks

Stu