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Help! Anyone who are familiar with spice3 source code?

Discussion in 'Electronic Basics' started by spice3, Jun 10, 2004.

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  1. spice3

    spice3 Guest

    My boss asked me to modify spice MOSFET model equation. I have studied
    spice3f5 source code a few days but I can't understand. There are too many
    files. I don't know even the basic structure of source code. I have only one
    month time. Is there anyone who can help me? Thanks in advance!
  2. Why?

    Which model, 1, 2, 3 bsim3?
    Maybe. What do you want to do. Some things are easy, some things you
    shouldn't mess with until you've figured out the code in more detail.
    Some things you should never mess with:)

    Kevin Aylward
    SuperSpice, a very affordable Mixed-Mode
    Windows Simulator with Schematic Capture,
    Waveform Display, FFT's and Filter Design.
  3. Mantra

    Mantra Guest

    Ditto on that. Messing with the MOS equations on Spice 2 or 3 can
    result in major accuracy and convergence problems that you may never
    solve. I've been using Spice and doing device model extraction for 20
    years and you couldn't pay me to jump into that code base to do that.
    And that's with 20 years of C (and C++, Java, etc.) experience to
    boot. I'd sooner start a new simulator from scratch.

    Generally for the average Spice user only want to mess with device
    models when you are using a Spice or Spice-like tool that was
    specifically designed for user modifications. The issue is that in
    Spice there are two areas of iterative numeric computation (non-linear
    DC analysis and then transient analysis) which can be seriously messed
    up with bad or malformed model equations. "Bad" can mean flawed
    companion model, 1st or 2nd derivative discontinuities, etc. Consider:
    why would everyone mess SUBCKTs or analog behavioral commands if you
    could easily write some C and drop it in? It's because you usually

    It should also be noted that most/all of the MOS models were
    originally PhD theses. Any one of the current models available will
    probably be better than what you come up with. Just food for thought.

    Despite that "fear-of-god" speech, here's a place to start. This is a
    nice online exposition of how Spice works:

  4. spice3

    spice3 Guest

    I need to add BSIMSOI3. I tried to add BSIM4 as a test according to
    instruction I got from berkeley website. But it can't work for bsim4. When I
    run a circuit example it always allert undefined parameter.

    I have studied spice3f5 souce code a few days. But I find I am wasting time.
    Can you give me a detailed description about spice3 source code?
  5. spice3

    spice3 Guest

    Thanks. Even if I will fail I want to have a try. I found the website you
    listed. There are lots of useful information. But I can't find anything
    about the organization of spice source code.

    I am doing parameter extraction too. Can you tell me which tools have you
    used to extract model parameter? I have extract model parameter for SOI PD
    MOSFET. But there are two problem:
    1. The simulation curve can't simulate kink effect.
    2. The simulation curve is quite different with measure curve when a
    substrate voltage is added.

    My tutor said maybe the soi model is not mature. He asded me to modify the
    model equation and extract parameters. He doesn't realize the hardness of
    the work. I need to find a more accurate model equation that can simulate
    kink effect. Then I need to modify model equation in spice. Finally I need
    to extract model parameter.

    These days I feel I am wasting time. I can't get any progress.
  6. lrzh2000

    lrzh2000 Guest

  7. spice3

    spice3 Guest

    I have sent you my spice3. Have you had a look?
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