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 How to plot device parameters from transient sims. 

Last post Thu, Jan 17 2013 1:23 AM by Andrew Beckett. 6 replies.
Started by Eric Gamble 21 Oct 2008 04:15 PM. Topic has 6 replies and 7304 views
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  • Tue, Oct 21 2008 4:15 PM

    • Eric Gamble
    • Not Ranked
    • Joined on Tue, Oct 21 2008
    • Hillsboro, OR
    • Posts 4
    • Points 80
    How to plot device parameters from transient sims. Reply

    Hello,

     

      I would like to plot gm, gds, cgs, cgd, etc. as a function of time in my spectre transient sims using analog artist.  How do I do this?

     

    Thanks, Eric.

    • Post Points: 35
  • Thu, Oct 23 2008 3:59 AM

    • haikom
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    • Joined on Thu, Oct 16 2008
    • Berlin, Berlin
    • Posts 12
    • Points 165
    Re: How to plot device parameters from transient sims. Reply

    Hi,

    if these parameters are stored in the results / psf folder, you can use the OCEAN commands to plot them. Therefore you have to do the following steps:

    Open the results:

        - e.g.  openResults("/myAbsolutePath/...../...../psf")

    Select the results:

        - e.g.  selectResults('tran)

        - you can use results() to display the selectable relults --> (dc tran ac)

    Get the waveform Id:

    e.g.  wId = getData("net0815")  --> waveform Id drwave:24234545

    Plot the waveform:

    e.g. plot("wId")

    If you have to calculate the parameters, you can use the OCEAN waveform calculator command described in the OCEAN reference.

    Regards

    haiko

    • Post Points: 20
  • Thu, Oct 23 2008 9:16 AM

    • Eric Gamble
    • Not Ranked
    • Joined on Tue, Oct 21 2008
    • Hillsboro, OR
    • Posts 4
    • Points 80
    Re: How to plot device parameters from transient sims. Reply

     Hi haiko,

     

      Thank you for your response.  Unfortunately it does not answer my question.  Let me try to be more specific:

    I already know how to open results, view and plot voltages and  currents in ocean and analog artist.

    I want to plot the small signal parameters of the BSIM4 model of some transistors during a transient sim.  Particularly, I want to track how the gm, cgd, and cgs change as a function of time.  These are transistor parameters, not voltages and currents.

    How do I:

    1) save these in simulation

    and 

    2) plot them as a function of time.

    And just to be completely clear, I am NOT interested in the operating point of these devices at a single time step like you can access using the menu: Results -> Print -> Transient Operating Points  OR the calculator expression: OPT("/dut2/MNP" "gm") which only give me these parameters at a SINGLE point in time, not as a waveform in time.

    This is a trivial thing to do in HSPICE, so I assume it must be a trivial thing to do in Spectre and Analog Artist.  I just can't find it.

     

    Thank you,

    Eric.

     

    • Post Points: 5
  • Fri, Oct 24 2008 8:22 AM

    • Eric Gamble
    • Not Ranked
    • Joined on Tue, Oct 21 2008
    • Hillsboro, OR
    • Posts 4
    • Points 80
    Re: How to plot device parameters from transient sims. Reply

     Nevermind,

      Found it in SourceLink solution number 11003524.

    It turns out you need to create a text file that contains:

    save M1:oppoint M2:oppoint

    etc. for all the transistors and then access the data through the results browser.

    Not as easy as I expected it to be, but at least it's possible.

     

    Eric.

    • Post Points: 20
  • Mon, Oct 27 2008 1:17 AM

    • haikom
    • Not Ranked
    • Joined on Thu, Oct 16 2008
    • Berlin, Berlin
    • Posts 12
    • Points 165
    Re: How to plot device parameters from transient sims. Reply

    Hi Eric,

    I'm did not understand completely, what you want. The save statement "save M1:oppoint ..." seams to save the final operating point parameters. If you want to access theses values you can do this using the following way:

    \i results

    \o  (tranOp subckts instance "tranViolations-violations" model "tran-info" variables output designParamVals tran primitives)

    \i selectResults('tranOp)

    \o  stdobj@0xc36030c

    \i outputs

    \o --> a huge list with all possible outputs :)

    \i  m0Id=getData("I8_0.M0")

    \o dr:0xbb45018

    Now you can access the final operating point parameters (gm, gds, cgs ....) using the squiggle operator:

    \i m0Id~>cgs

    \o  -4.857316e-15

    Here you just have one value for the final operating point. You can carry out a parametric analysis to get an parameter plot e.b. cgs vs. Vds.

    Is this what you want?

    Regards

    haiko

    • Post Points: 5
  • Wed, Jan 16 2013 10:42 AM

    Re: How to plot device parameters from transient sims. Reply

    Hi eric,

    I am also facing the same problem , can you please tell me weather you got solution of this problem or not.

     

    Thanks & regards

    Prateek jain

     

    • Post Points: 20
  • Thu, Jan 17 2013 1:23 AM

    Re: How to plot device parameters from transient sims. Reply

    The Forum Guidelines tell you not to post on old threads (and this one was VERY old - more than 4 years old).

    And anyway, the answer was given by Eric in the thread, including a reference to a solution number on Cadence Online Support. This has been covered on numerous occasions on this forum too.

    Andrew.

    • Post Points: 5
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Started by Eric Gamble at 21 Oct 2008 04:15 PM. Topic has 6 replies.