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  3. sweeping w/L ratio

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sweeping w/L ratio

whlinfei
whlinfei over 16 years ago

Hi all,

 I am new to cadence and I tried to sweep a mosfet w/L ratio under a dc sweep. ( for every w/l , a gate bias dc analysis is run from 0 to Vdd).

However I tried to define my variable as "param" to indicate the number of fingers so that I could change the total width but couldt get the result.

 Can anyone help me with this ? 

I am using vurtuoso schematic to design and vurtuoso analog design environment to simumlate. 

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  • Andrew Beckett
    Andrew Beckett over 16 years ago

    To be honest, the solution is not going to help you very much anyway, because it's more about describing how to create a PDK which doesn't use callbacks, or uses them in such a way to not have this problem.

    I don't have access to the PDK you're using, so I can't offer that  much advice. When you enter a parameter name in the parameter field, do you get any errors in the CIW? CDF callbacks are defined in the CDF for each field for the component in question (you should be able to see them in Tools->CDF->Edit CDF and pick the component you're using), and are often used to derive one parameter from another. So for example, if you enter width and or fingers, and it auto-calculates total width, then that is done by a CDF callback. The question is often which parameters actually get netlisted - this is controlled by the simulation information section.

    The PDK User Guide (assuming there is one) may describe what is and isn't supported, so it's worth reading that. Essentially you can probably figure it out by entering parameters in various fields, checking for errors in the  CIW, and seeing what gets netlisted.

    Regards,

    Andrew.

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  • Andrew Beckett
    Andrew Beckett over 16 years ago

    To be honest, the solution is not going to help you very much anyway, because it's more about describing how to create a PDK which doesn't use callbacks, or uses them in such a way to not have this problem.

    I don't have access to the PDK you're using, so I can't offer that  much advice. When you enter a parameter name in the parameter field, do you get any errors in the CIW? CDF callbacks are defined in the CDF for each field for the component in question (you should be able to see them in Tools->CDF->Edit CDF and pick the component you're using), and are often used to derive one parameter from another. So for example, if you enter width and or fingers, and it auto-calculates total width, then that is done by a CDF callback. The question is often which parameters actually get netlisted - this is controlled by the simulation information section.

    The PDK User Guide (assuming there is one) may describe what is and isn't supported, so it's worth reading that. Essentially you can probably figure it out by entering parameters in various fields, checking for errors in the  CIW, and seeing what gets netlisted.

    Regards,

    Andrew.

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