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    auCdl netlist parameter: nf

    Usually where do people find the documentations to understand those parameters in, say, a auCdl spice netlist?

    Anyone know what "nf=" in a MOS instance in the netlist mean?
    In Calibre LVS, I have a MD(pfet) of w=2u and nf=1 from layout, but a MD(pfet) of W=8u and nf=pfolds from the schematics (pfolds = 4); this make me guess that "nf=" somehow relates to "m="...

    Because this kind of discrepancies w=2u nf=1 versus w=8u nf=4, LVS is not clean :(

    Any suggestions? Thank you in advance

    •   Alt10th July 2010, 16:36

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    Re: auCdl netlist parameter: nf

    That kind of info is in the SPICE MOS-modeling docs. I have the docs for HSPICE but can't share due to copyright. I can tell you:

    NF = number of fingers for fingered MOSFETS. i.e.:
    Code:
    M1 out in vdd vdd pmos w=10u l=1u nf=5
    means M1 has a total drawn width of 10um with 5 fingers, each having a finger gate width of 2um.

    'm=XXX' is the multiplicity factor. It means that 'M' identical transistors are in parallel. For example:
    Code:
    M2 out in vdd vdd pmos w=10u l=1u m=5
    Means 5 identical transistors are in parallel for a total width of 50um.

    w=2u nf=1 versus w=8u nf=4 are definitely not the same and you have some kind of mismatch that should be checked.
    Code:
    ... w=2u nf=1
    Means one transistor 2um wide with one finger.
    Code:
    ... w=8u nf=4
    Means one transistor 8um wide with 4 fingers 2um wide each.

    I've never heard of pfolds and it's not in my spec.
    Hope that helps!


    2 members found this post helpful.

    •   Alt10th July 2010, 19:42

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  3. #3
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    Re: auCdl netlist parameter: nf

    Thank you!

    Hmm, I will look into LVS more carefully...



    •   Alt10th July 2010, 19:48

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    Re: auCdl netlist parameter: nf

    Hi There,
    I'm using Hspice for simulating a circuit in which there are pmos and nmos transistor with 500000um and 300000um width respectively. I have been trying to use multiplier(m) and fingure(nf) to shorten these transistors.Unfortunately I have got a problem with NF. And I don't know how I can solve it. I use 0.18um CMOS technology. Could you possibly help me?
    I look forward to hearing from you.
    Best Wishes,
    Ebi



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