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Parameters of a FINFET

ElectronLearn

Hi all,

I am new learner of Cadence. While I was performing simulations using FINFET as a device, I found out the voltage across the device using two methods :-

1. By taking node voltages difference

2. Printing the dc operating points of the device and looking at Vds.

These two are not matching. However its matching with one another parameter written as Vdet. I just want to know what all these voltage parameters represent.

Vdet, Vds, Vdssat, Vdst, Ves, Vest, Vfb, Vgd, Vgdt, Vget, Vgs, Vgst, Vgt and Vth.

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  • Andrew Beckett

    For details of what all these operating point parameters are, you can get a first-level understanding simply by looking at "spectre -h bsimcmg" (in the Operating Point Parameters section). The parameters vds, vgs, vgd, ves, vde and vge are the drain-source, gate-source, gate-drain, bulk-source, drain-bulk and gate-bulk voltage of the intrinsic device (i.e. the transistor inside, excluding the terminal resistances). The same parameters with a "t" on the end are the parameters to the terminal. So the vdet parameter is the drain-bulk terminal voltage (I suspect you really want vdst but maybe your source and bulk are connected, so they'd be the same). The others you mention are vdssat (Drain-Source Saturation Voltage), vfb (Flatband Voltage), vgt (effective gate drive voltage) and vth (threshold voltage). 

    Note that not every combination of the parameters with and without the t are available (I think some are missing without the t).

    For more details you'd need consult the Berkeley code and documentation, http://bsim.berkeley.edu/models/bsimcmg/ - although to be honest these don't cover parameters like vest - I think we probably ought to do a better job of documenting these (so I'd suggest you contact customer support and request a documentation improvement to be more explicit about the meaning of these operating point parameters; a few years back we did this with bsim4 and put hyperlinks into the documentation to point to the equations for operating point parameters or added more detail where needed).

    Regards,

    Andrew.

  • ElectronLearn
    in reply to Andrew Beckett

    Thank you very much Andrew. One thing that I didn't get here is where do I find this "spectre -h bsimcmg" (Operating Point Parameters section).

  • Andrew Beckett
    in reply to ElectronLearn

    In the UNIX terminal, type "spectre -h bsimcmg". Or run `spectre_root`/bin/cdnshelp (at the UNIX prompt) and look in the Spectre Model Reference manual. Or type "spectre_root" in the terminal and open <SPECTREinstDir>/doc/spectremod/spectremod.pdf and look in the bsimcmg chapter.

    Andrew

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  • Andrew Beckett
    in reply to ElectronLearn

    In the UNIX terminal, type "spectre -h bsimcmg". Or run `spectre_root`/bin/cdnshelp (at the UNIX prompt) and look in the Spectre Model Reference manual. Or type "spectre_root" in the terminal and open <SPECTREinstDir>/doc/spectremod/spectremod.pdf and look in the bsimcmg chapter.

    Andrew

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