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Layout Parasitic Extraction capacitance filter

milind0y

Hi,

    I am trying to extract a block layout to do extracted simulations. I set the MinC value for coupled capacitor extraction to 20fF. But in the netlist I still see capacitors below 1fF in value. Why am I seeing these small capacitances?

Thanks,

Milind

  • Hi Milind

    Actually minC option does not remove the caps. It is not the same as minR which really removes the parasitic resistors. minC only decouples capacitors. Suppose there is a 1f parasitic cap that couples netA and netB. if minC=2f, Quantus (new name for QRC) will decouple the cap. This means that we will have 2 new 1f caps (netA->gnd and netB->gnd).

    If you would like to reduce the number of parasitic devices, you can enable "Parasitic reduction" in "Filtering" tab in the Quantus form.

    Best regarsd
    Quek

  • Hi Guys,

    Can anyone explain what the '%' dialog box means for the Cmin option in the Filtering tab of the QRC form ?

    Thanks,

    Niall.

  • Hi Guys,

    Can anyone explain what the '%' dialog box means for the Cmin option in the Filtering tab of the QRC form ?

    Thanks,

    Niall.

  • Hi Niall

    The value is a percentage of the total capacitance on the net. Please refer to $QRC_HOME/doc/extUser/extUser.pdf for more details. By the way, it would be great if you are start new threads for your own question. : )

    Best regards
    Quek

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