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    Problem in plotting I/O waveform in Cadence

    Hello

    I want to plot the I/O characteristics of PFD to see the dead zone. I got to know from the previous post that I have to plot the current and sweep variable, but can anyone please elaborate the process on how to sweep the variable.


    Thanks

    Nigidita

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    Re: Problem in plotting I/O waveform in Cadence

    What do you mean by “in Cadence” ?
    Do you visit Cadence office and are you there now ?

    https://www.edaboard.com/showthread.php?345554



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    Re: Problem in plotting I/O waveform in Cadence

    By cadence I mean using cadence EDA tool.



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    Re: Problem in plotting I/O waveform in Cadence

    Quote Originally Posted by Nigidita View Post
    By cadence I mean using cadence EDA tool.
    Cadence have many many tools.
    No one knows what tool you use.



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    Re: Problem in plotting I/O waveform in Cadence

    Actually I am new in this.. I am using cadence virtuoso...



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    Re: Problem in plotting I/O waveform in Cadence

    Quote Originally Posted by Nigidita View Post
    I am using cadence virtuoso...
    It is a design framework.



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    Re: Problem in plotting I/O waveform in Cadence

    I want to sweep the phase of Fref and Fdiv .... I have done dc analysis in cadence virtuoso ADE enviroment..... I am not sure which parameter to sweep and how to sweep. Is it AC phase or delay time? I have attached the picture below.. Please have a look.
    Click image for larger version. 

Name:	plotingproblemofphase.jpg 
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Size:	313.0 KB 
ID:	155467



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    Re: Problem in plotting I/O waveform in Cadence

    Can you undestand your circuits ?

    DC Analysis is not useful.

    You have to do Transient Analysis or Shooting-Newton-PSS Analysis.

    Show me netlist.
    Last edited by pancho_hideboo; 11th September 2019 at 14:46.



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    Re: Problem in plotting I/O waveform in Cadence

    I have done the transient analysis and checked the working... but I was not able to get current vs phase plot...please see the netlist.

    Click image for larger version. 

Name:	cHARGEPUMP pfd.png 
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    Re: Problem in plotting I/O waveform in Cadence

    Quote Originally Posted by Nigidita View Post
    please see the netlist.
    Can you understand netlist ?
    Show me netlist.



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    Re: Problem in plotting I/O waveform in Cadence

    I think this is the netlist.

    netlist.txt



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    Re: Problem in plotting I/O waveform in Cadence

    Quote Originally Posted by Nigidita View Post
    Hello

    I want to plot the I/O characteristics of PFD to see the dead zone. I got to know from the previous post that I have to plot the current and sweep variable, but can anyone please elaborate the process on how to sweep the variable.


    Thanks

    Nigidita
    Connect a capacitor to your charge pump output. Make sure its large enough so that when the CP turn on, the voltage does not change too much.

    Start with two vpulse sources that have a phase offset between them as a parameter. Run a transient simulation and see how much charge is dumped into your capacitor (the difference in voltage before up or down went became high and voltage after both of them became low multiplied by the capacitance). And then you do a parametric sweep on the offset.

    Ideally, for a 20ps phase offset, the amount of charge dumped will be 2x charge dumped for a 10ps offset.

    By the way, I really don't see the point in measuring deadzone like this. The thing you need to ensure is that for your minimum reset pulse width, both the current sources turn on and settle to their final DC values in the slowest corner.



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    Re: Problem in plotting I/O waveform in Cadence

    Last edited by pancho_hideboo; 12th September 2019 at 13:58.



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    Re: Problem in plotting I/O waveform in Cadence

    I have taken vpulse source it has AC phase and delay time.... which one should I take?



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    Re: Problem in plotting I/O waveform in Cadence

    I have done the transient analysis I got this result.... How can I get phase in X-axis?
    Click image for larger version. 

Name:	1.png 
Views:	6 
Size:	109.9 KB 
ID:	155495



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    Re: Problem in plotting I/O waveform in Cadence

    Use the delay function to plot the delay between the two wave-forms and then do a Y vs Y plot.
    Alternatively you can save both your voltage/current/charge waveform and your delay waveform in csv files and plot them in Matlab/Python/Julia etc

    Here is an example of a sample delay function:

    Code:
    delay(?wf1 v("/feedback" ?result "tran"), ?value1 0.5, ?edge1 "rising", ?nth1 1, ?td1 0.0, ?tol1 nil, ?wf2 v("/ref" ?result "tran"), ?value2 0.5, ?edge2 "rising", ?nth2 1, ?tol2 nil,  ?td2 nil , ?stop nil,  ?period1 1 ?period2 1 ?multiple t ?xName "trigger" )
    Make sure you select multiple and not single.


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