parameterized cells vs dfIIToVldb and assura

Hi,

I have a cell which is parameterized in the schematic. dfIIToVldb is
not happy about it. For example on a MOS transistor in the cell I have
something like:

w = pPar("Width")
l = pPar("Length")

where w and l are both CDF parameters. There is also an 'as' CDF
parameter which is not editable and is set by the callback to something
like (w+dlw)*(l+dll) so in the property form for the device I see
something like

(pPar("Width")+1u)*(pPar("Length")+1u) M

(exact values not listed, but this should show the issue).

Now if you list 'as' in the instParameters you end up getting

*Error* Param 'as' on inst 'I1' in 'mycell schematic mylib' cannot be
evaluated

during the dfIIToVldb part in an assura lvs run.

Any ideas on what one must do to get this to work correctly?

Thanks
-Dan

 

We do this a lot, it works in Virtuoso/Assura, and has for
years.

The only example you gave was for as, that confuses me a
bit (unless you're comparing as in LVS). What is the error
message you get for w and l?

A careful look at the auLvs cellviews is called for.

-Jay-

 

I have a cell which is parameterized in the schematic. dfIIToVldb is

sure, that will work only if the parameters are assigned a value in some way.
i.e., you have to instanciate your cell in another one and assign a value to
these parameters. is this what you do? or are you trying to verify this very cell?

stéphane

 

Hm. I didn't get any error for w and l. I don't see anything
interesting in the auLvs cellview, isn't that basically the same as the
symbol view? I thought all the "action" was in the CDF for the cell
and in the callbacks.

The CDF parameters which cause problems seem to be those which have
been automatically calculated via a callback. In other words, I bring
up the edit object properties form and put in pPar("Width") as the
value for w. The "as" box is not editable and it is the callback
specfied in the CDF which fills in that box.

I'm sure there is something silly going on here. Are there any good
tips for debugging the dfIIToVldb step?

Thanks
-Dan

 

Hi Stéphane,

This cell has defaults (numerical) for the parameters which happen to
match the values used in the cell which instantiates this block.

In this case I am trying to verify a cell which uses this lower level
one and the top level cell in question here puts in a number (like 4u)
for Width and Length.

-Dan