LTspice FFT Result Visualization Difficulty

Hi,

   I am using LTspice on the circuit EMI spectrum study. Let's say I have two waveforms for V1 and V2. I wonder if in LTspice, I can plot the FFT results for : 

   (1) V1+V2

   (2) FFT(V1) and FFT(V2) on the same figure

  I tried but it does not seem LTspice support these functions. Could anyone help me with LTspice? Thanks for help!

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  • 0
    •  Analog Employees 
    on Jan 29, 2019 5:15 PM

    Leey~,

    I'm sure there's more than one way to approach this, but I had success using an arbitrary behavioral voltage source (bv) to add the voltage of two nodes.  I also didn't have any trouble adding more than one node to an FFT plot.  By default, they were all overlaid on top of each other, but I was able to split the up by adding plot planes and dragging the curves to individual plot planes:

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  • 0
    •  Analog Employees 
    on Jan 29, 2019 5:15 PM

    Leey~,

    I'm sure there's more than one way to approach this, but I had success using an arbitrary behavioral voltage source (bv) to add the voltage of two nodes.  I also didn't have any trouble adding more than one node to an FFT plot.  By default, they were all overlaid on top of each other, but I was able to split the up by adding plot planes and dragging the curves to individual plot planes:

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