Difference between extracted values of a resistor

[bbbb]

Hi

When we extract a circuit by diva and assura we get different values for resistors (actual resistors, not parasitics) the difference is about 10-15%. and therefore there is a LVS error. for example:

Designed (layout) : 1K
extracted by Diva: 1.09K
extracted by Assura: 0.88K

Has anyone observed this and knows why?

 

[elektronixs]

they might used different value of sheet resistance since they have different rulefile...

 

[Fom]

I don't know about Assura, but as I remember Dracula and Diva return different value of resistors if they shape is different from rectangular (for example bent resistor). Calculation algorythm is different.

 

[Hughes]

The algorithm is defined by the rules. You have different rules, so you get different values.
You may try to use your diva extraction rule with Assura and check if there is any difference.

 

[bbbb]

Thanx for the comments, calcualtion algorithms seem to be different, but as the rule files are provided by the fab, I wonder which one is 3 values given by virtuso, diva and assura is more accurate?