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    How to plot MOSCAP C-V curve using Cadence Spectre in ADE?

    How to plot a MOSCAP capacitance versus Vg using Cadence ADE and Spectre?

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    Re: How to plot MOSCAP C-V curve using Cadence Spectre in AD

    for moscap, C-V fullfill the formular: V=I*Z=I/(jwc) , so |C|=|I/(w*V)|
    if V=1,w=1 then C=I

    Insert a dc voltage source in the gate of moscap, set the "ac amplitude" to 1 and dc voltage to "Vin". Do ac simulation and sweep the parameter of Vin from -2V to 2V at frequency "1". Plot ac current "I" of the terminal "G" and the C will be the same as I.

    Lorry


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    Re: How to plot MOSCAP C-V curve using Cadence Spectre in AD

    Quote Originally Posted by sharpsheep
    Insert a dc voltage source in the gate of moscap, set the "ac amplitude" to 1 and dc voltage to "Vin". Do ac simulation and sweep the parameter of Vin from -2V to 2V at frequency "1".
    Lorry
    Hi,

    Just to be sure.
    What do you mean by "at frequency "1"" ? The real frequency f or w ?
    I think you mean w. Is it that ?

    Actually, w=2×Π×f, if I wanna have w=1 I have to setup f=0.159 Hz.

    What about amplitude of the ac signal. Why set it to 1 ?
    Why not Vdd ?

    Thanks in advance for you reply.

    Advares.



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    How to plot MOSCAP C-V curve using Cadence Spectre in ADE?

    Or you could step V in a DC OP simulation, Parametric
    Analysis, and just plot op(cgg). If you're not set on directly
    emulating the measurement setup.

    If you set the measurement signal large then your C will be
    changing all the time, and since it's nonlinear you can't just
    go and average it. Though in AC analysis it's all bogus, if
    you ran a transient you'd see C varying across the cycle at
    1V amplitude (especially if you're swinging across inversion
    threshold). Setting input amplitude to 1 for AC is just a simple
    default and often makes the output amplitude be a useful
    datum directly (like, if input=1 then output amplitude also
    = gain).

    I'd be applying transient stimulus amplitude that is maybe 1%
    of full span, if I wanted 1% kind of accuracy where things are
    changing a lot.


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    How to plot MOSCAP C-V curve using Cadence Spectre in ADE?

    You could charge it with a constant current in a transient analysis and plot the slope.

    Keith
    I started life with nothing and I've still got most of it left. (Seasick Steve)



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