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 transient analysis for CV plot 

Last post Wed, Oct 24 2012 6:02 AM by soathana. 6 replies.
Started by soathana 24 Oct 2012 01:48 AM. Topic has 6 replies.
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  • Wed, Oct 24 2012 1:48 AM

    • soathana
    • Top 500 Contributor
    • Joined on Fri, Jan 13 2012
    • Posts 24
    • Points 360
    transient analysis for CV plot Reply

    Hi everyone,

    I want to maka a CV plot of MOSFET capacitances. By using ac analysis this is easy. The problem is that i want to keep all dc sources because they are used to bias some other controlling part of circuit. In essense I want to do transient analysis and sweep a dc source at the same time. How is this possible through cadence? 

    thanks,

    sotiris 
    • Post Points: 20

  • Wed, Oct 24 2012 5:20 AM

    Re: transient analysis for CV plot Reply

    Hi Sotiris,

    How do you want to sweep the source? It's not that clear to me. You could make the source a vsource from analogLib which is a pulse source ramping the value up during the transient; in non-transient analyses it will use the dc value of this source (if supplied) or the time-zero value if the dc value is not supplied.

    Or you could use the dynamic parameters capability of tran analysis to ramp up a variable (assigned as the value of the source) over time.

    Or you could use parametric analysis to sweep the source separately from the time sweep (this is if you want the sweeps to be orthogonal).

    As you can see I'm having to guess a little what your objective is.

    Andrew

    • Post Points: 20

  • Wed, Oct 24 2012 5:36 AM

    • soathana
    • Top 500 Contributor
    • Joined on Fri, Jan 13 2012
    • Posts 24
    • Points 360
    Re: transient analysis for CV plot Reply

    Hi Andrew and thanks for your fast response!

    I am using a vsin source and i want for a specific frequency to sweep its dc offset (or a dc voltage source in series).

    thanks,

    Sotiris 
    • Post Points: 20

  • Wed, Oct 24 2012 5:40 AM

    Re: transient analysis for CV plot Reply

    Sotiris,

    It's still not that clear to me...

    Andrew.

    • Post Points: 20

  • Wed, Oct 24 2012 5:50 AM

    • soathana
    • Top 500 Contributor
    • Joined on Fri, Jan 13 2012
    • Posts 24
    • Points 360
    Re: transient analysis for CV plot Reply

    Ok, probably it is Dynamic parameter option... I will work it out

    thanks,

    sotiris 
    • Post Points: 20

  • Wed, Oct 24 2012 5:58 AM

    Re: transient analysis for CV plot Reply

    Sotiris,

    OK, so are you expecting to have a vsin source with a specific frequency, and then have the DC voltage change during the transient simulation. Or do you want to several transient simulations with different DC offsets?

    Andrew

    • Post Points: 20

  • Wed, Oct 24 2012 6:02 AM

    • soathana
    • Top 500 Contributor
    • Joined on Fri, Jan 13 2012
    • Posts 24
    • Points 360
    Re: transient analysis for CV plot Reply

    Hi Andrew, 

    sorry for the many edits. I need a vsin source with a specific frequency, and then have the DC voltage change during the transient simulation. I tried with dynamic parameters a little bit, so I made a file for DC voltage with respect to time:

     

    "tscale 1e-6

    time value

    0   -5

    100 -4.5

    ...

    2000 5"

     

    And I have tran 2m.

    Is this the way to do it? Also is there a way to make it look more continuous. When I plot it with respect to time i get steps...

    Also is there a way to plot versus the dynamic parameter instead of time?

    Thanks,

    Sotiris 

     
    • Post Points: 5
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Started by soathana at 24 Oct 2012 01:48 AM. Topic has 6 replies.