Problem with Diva LVS when using multi-finger transistors

[truejiaqi]

Hi, I am using Diva LVS checking my design. But there is a strange phenomena that, when I use muli-finger transistors, it can not recognize the multiplication factor in the device properties in schematic. Therefore it generates errors about Size mismatch errors.
For instance, I have a pmos with w/l=10u/1u, and multiplication factor = 2. In the layout extraction Diva calculated successfully that I have a transistor with w=20u,l=1u. But for the schematic it did not understand that there is a factor of 2. So the error is: Size mismatch; layout W/L: 20u/1u, schematic W/L: 10u/1u.

Does anybody have some idea what could be wrong?
Thanks a lot!

 

[rf_ray]

diva lvs cdf parameter

In schematic , try to play with number of fingers and multiplication factor, I guess one of them will reflect the layout finger number.

 

[truejiaqi]

diva lvs

there is only a field called "multiplication factor" in the transistor properties, and I have set it to the correct value. Diva just does not understand it.

 

[giedrius]

Re: Diva LVS problem

Hi, I am using Diva LVS checking my design. But there is a strange phenomena that, when I use muli-finger transistors, it can not recognize the multiplication factor in the device properties in schematic. Therefore it generates errors about Size mismatch errors.
For instance, I have a pmos with w/l=10u/1u, and multiplication factor = 2. In the layout extraction Diva calculated successfully that I have a transistor with w=20u,l=1u. But for the schematic it did not understand that there is a factor of 2. So the error is: Size mismatch; layout W/L: 20u/1u, schematic W/L: 10u/1u.

Does anybody have some idea what could be wrong?
Thanks a lot!

Hi,

I think your lvsRules(...) don't support that device permuting. Try to place transistors to schematic in the same way like in layout is done.

Giedrius

 

[sat]

Diva LVS problem

Check the following:
1. Before you start icfb or layout or layoutplus:
---------------------------------------------
% setenv CDS_Netlisting_Mode Analog
---------------------------------------------

2. Make sure the Schematic netlist is having the multiplier (m=2), if not, you need to instruct the tool to output that during netlisting.

2.a.
How to control - what parameters will get netlisted out?
CIW (Top Menu) -> Tools ->CDF -> Edit;
in the Edit Component CDF form, select the device_library, and cell (for example, pmos). [ select CDF Type = Base ]

-> The form will be populated with parameters and values.

Scroll down to the section called "Simulation Information" -> click on "Edit" button, then 'Choose Simulator' set to "auLvs"

check out "instParameters" - l w m
[ They are length width and multiplier parameters ]
You may also need to check propMapping if there is any.
[ m is the multiplier, it can be M or mul etc, which you can check from main CDF-Edit form->Component parameters section-> Edit ->select the appropriate name etc ]

3. Check the divaLVS rule file and check if it is using native merge and comparison or user supplied SKILL, find if any glitches.

Or, simply visit h**t://sourcelink.cadence.com and if you have sourcelink ID, open a ticket - the support group should be able to help you better - I guess.