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Parasitic capacitances from printed DC operating point of Spectre (with BSIM3v3)

Dancing Wave

Hi all,

I have a  question to ask about BSIM model, I hope it will not take too much time for you to answer this question. Since now I am using a BSIM3.3 0.18-um CMOS model in my work (Cadence, Spectre) and I am wondering about how to figure out the total parasitic capacitances of a transistor. In PSPICE, after I ran a simulation and click on the Probe window to see the output file, I can see a list of small-signal parameters saying that, for example, Cgs = 10 fF (for intrinsic), Cgsov = 20 fF (for overlap capacitance), etc.

However, for BSIM3.3 and for Spectre simulator, I received a set of small-signal parameters after running a simulation, for example, as shown in the attached file. For these parameters, for the capacitances, I don't know how to calculate the total intrinsic and extrinsic capacitances since they are separated into several capacitances. Would you mind to explain me a little bit about this  ?

Parents

  •  Hi Jim,

    Thank you very much for the information. I am having a look at the document you mentioned. However, it seems that I am not being able to figure out how to calculate the real intrinsic Cgs, for example. Did you really see Cgs, Cgsov parameters like this from Results --> Print --> DC operating point ?? For my case, as shown in the attached picture, my Cgs is negative and there are also Cgg, Csg, Cdd .., etc. So from this output data, I am very confused about how to calculate the effective value of, for example, intrinsic Cgs.

    Would you mind to suggest again :)

     WD

Reply

  •  Hi Jim,

    Thank you very much for the information. I am having a look at the document you mentioned. However, it seems that I am not being able to figure out how to calculate the real intrinsic Cgs, for example. Did you really see Cgs, Cgsov parameters like this from Results --> Print --> DC operating point ?? For my case, as shown in the attached picture, my Cgs is negative and there are also Cgg, Csg, Cdd .., etc. So from this output data, I am very confused about how to calculate the effective value of, for example, intrinsic Cgs.

    Would you mind to suggest again :)

     WD

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