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Different Extracted Capacitance Values of the Same MOM Cap Structures Obtained from Quantus QRC Filed Solver

baltacican87

Hello,

 

I am using Virtuoso 6.1.7.

 

I am performing the parasitic extraction of a MOM cap array of 32 caps. I use Quantus QRC and I enable field solver. I select “QRCFS” for field solver type and “High” for field solver accuracy. The unit MOM cap is horizontally and vertically symmetric. The array looks like the sketch below and there are no other structures except the unit caps:

Rationally speaking, the capacitance values of the unit caps should be symmetric with respect to a vertical symmetry axis that is between cap16 and cap17 (shown with dashed red line). For example,

the capacitance of cap1 should be equal to the capacitance of cap32

the capacitance of cap2 should be equal to the capacitance of cap31

etc. as there are no other structures around the caps that might create some asymmetry.

Nevertheless, what I observe is the following after the parasitic extraction:

As it can be seen, the result is not symmetric contrary to what is expected. I should also add that I do not observe this when I perform parasitic extraction with no filed solver.

Why do I get this result? Is it an artifact resulting from the field solver tool (my conclusion was yes but still it must be verified)? If not, how can something like this happen?

 

Many thanks in advance.

 

Best regards,

Can

  • Andrew Beckett

    Hi Can,

    I would suggest you contact your account team or customer support. The QRCFS option has been replaced by a newer "Quantus FS" option which has higher accuracy and also has an additional "high_accuracy" mode which increases the accuracy still. The older QRCFS is no longer under active support, so it would make much more sense to migrate to the newer version and newer option. It's possible this might require updates to your licensing, hence my suggestion to contact your account team.

    Kind Regards,

    Andrew.

  • baltacican87
    in reply to Andrew Beckett

    Hi Andrew,

    Many thnaks for your response. I will check it with my team and see if I can perform parasitic extraction in "Quantus FS".

    Best regards,

    Can

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