LVS of a black box

[Karen]

Hi,

I have a standard cell flip flop for which I only have the layout view,
and the schematic is only a bunch of pins. I am trying to run LVS at a
higher level cell, and it always fails. I added the "lvsIgnore"
property to the dff's symbol view but my LVS still says that the
netlists are different. They surely are, as the transistors for the dff
do exist in the layout view. Is there another way to do LVS when you
have a layout but you don't have a schematic view for it?

Thanks!

 

[Edward Kalenda]

On 5 Jun 2006 15:58:03 -0700, "Karen" <karenmgonzalez@hotmail.com>
wrote:

Hi,

I have a standard cell flip flop for which I only have the layout view,
and the schematic is only a bunch of pins. I am trying to run LVS at a
higher level cell, and it always fails. I added the "lvsIgnore"
property to the dff's symbol view but my LVS still says that the
netlists are different. They surely are, as the transistors for the dff
do exist in the layout view. Is there another way to do LVS when you
have a layout but you don't have a schematic view for it?

Thanks!

My comments assume you are using Diva. If you are using something else,
what follows won't work.

You want to do a macro cell extract before running LVS. Create a macro
cell file identifying as "macro" the cells which you do not have
schematics for. The last line should use wildcards to identify
everything else as "graphic". Use an RSF file to load the macro cell
file. See the Diva Reference Manual for details.


in macros.txt:

# layout cells which should be treated as primitives
mylib ff1 layout macro
mylib inv layout macro

# everything else should be expanded
* * * graphic


in myrsf.txt:

# load the macro cell file
macroCellFile("macros.txt")


If using ivVerify from the Unix command line:
ivVerify extract top layout -rsf myrsf.txt -macro -echo

Or select macro cell mode in the Extract form, check the Use RSF File
box and enter the RSF file name in the field for it.

An alternate approach that avoids the need for macros.txt and myrsf.txt
is to modify the layout cell views by adding the ivCellType property
with a value of "macro" to the ones that should be treated as primitive
devices. The down side to this is it applies to everybody using the
library and requires write access to the cell views.