When using LTspice, I can see the FFT of a voltage. How can I see how much power is in a particular frequency band, and what portion of the total power it is?
The FFT in LTspice is in dB, but it's not clear what the dB are relative to.
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2\$\begingroup\$ If you ask it for the FFT of a node voltage, then it's dB voltage, not dB power. \$\endgroup\$– AaronCommented Jul 1 at 19:51
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\$\begingroup\$ The FFT scaling is in dBV RMS. You can right-click on the FFT scale and select linear, log, and dB scaling. Perhaps this discussion answers your question. You may want to do the calculations in a maths program. LTspice allows you to export data to a text file (right-click in the middle of the graph). \$\endgroup\$– qrkCommented Jul 1 at 20:30
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