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stb Ocean/Skill examples

dlbro

Does anyone have any examples of using the stability analysis (stb) Sprectre tool in Ocean/Skill? I've done extensive scripting in transient, AC, DC, noise, pnoise, etc... but this is the first time I've tried stb. Running stb is easy, I've seen some stuff on how to do phase margin and gain margin, but how do I plot the gain and the phase? I've searched Cadence and Source link and the internet to no avail. Is there any equivalent to VT(), VF(), VS() for stb?

Thanks in advance,

dlb

Parents

  • Hi Dave,

    I'll step you through the process (even though you have a solution).

    1. Run the simulation with stb analysis enabled (in ADE)
    2. Results->Direct Plot->Main Form and select the stb analysis.
    3. Choose what you want to plot (e.g. Loop Gain, Magnitude, db20), and then hit the "Add To Outputs" button on this form. Similarly you could pick Phase Margin and "Add To Outputs"
    4. OK or Cancel the direct plot form (no need to plot anything)
    5. In the ADE Outputs pane you should see two outputs (if you did the above two choices) called "Loop Gain dB20" and "Phase Margin". Double click on one of these, or choose the Outputs-> Setup menu and select the output you are interested in.
    6. You'll see that the expression for loop gain is db(mag(getData("loopGain" ?result "stb"))) (essentially the same as what you found from the results browser), and Phase Margin is getData("phaseMargin" ?result "stb_margin") - you can cut and paste these expressions to your OCEAN script.

    This general "Add To Outputs" technique is often very useful.

    For saving an OCEAN script, do Session->Save OCEAN Script in your ADE window - any of the signals/expressions which are in your Outputs pane (added with "Add to Outputs" will be in the script.

    Hope that clarifies things,

    Regards,

    Andrew.

Reply

  • Hi Dave,

    I'll step you through the process (even though you have a solution).

    1. Run the simulation with stb analysis enabled (in ADE)
    2. Results->Direct Plot->Main Form and select the stb analysis.
    3. Choose what you want to plot (e.g. Loop Gain, Magnitude, db20), and then hit the "Add To Outputs" button on this form. Similarly you could pick Phase Margin and "Add To Outputs"
    4. OK or Cancel the direct plot form (no need to plot anything)
    5. In the ADE Outputs pane you should see two outputs (if you did the above two choices) called "Loop Gain dB20" and "Phase Margin". Double click on one of these, or choose the Outputs-> Setup menu and select the output you are interested in.
    6. You'll see that the expression for loop gain is db(mag(getData("loopGain" ?result "stb"))) (essentially the same as what you found from the results browser), and Phase Margin is getData("phaseMargin" ?result "stb_margin") - you can cut and paste these expressions to your OCEAN script.

    This general "Add To Outputs" technique is often very useful.

    For saving an OCEAN script, do Session->Save OCEAN Script in your ADE window - any of the signals/expressions which are in your Outputs pane (added with "Add to Outputs" will be in the script.

    Hope that clarifies things,

    Regards,

    Andrew.

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