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#1
06-04-2011, 03:24 PM
 atferrari Senior Member Join Date: Jan 2004 Location: Buenos Aires - Argentina Posts: 1,545
FFT in LTSpice

LTSpice

I am confused about this: what it is the actual reference (0 dB) as shown in the graphic of a FFT from a certain signal?

In other words, the level of the harmonic content, is it compared to what?
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Agustín Tomás

In theory, there is no difference between theory and practice. In practice, however, there is
#2
06-04-2011, 07:46 PM
 debjit625 Senior Member Join Date: Apr 2010 Location: Blue planet... Posts: 790

Normally the FFT shows the result in decibel but you can change the unit to Volts or Amp,use "linear" option to repersent the magnitude.To, get the option window in LTSpice click on the decibel units on FFT window.

Good Luck
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Debjit Roy
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#3
06-05-2011, 02:56 AM
 Ron H E-book Developer Join Date: Apr 2005 Location: Idaho, USA (GMT-7) Posts: 7,050

I ran a little experiment on a 1kHz sine wave. 1V RMS = 0 dB.
#4
06-05-2011, 12:30 PM
 atferrari Senior Member Join Date: Jan 2004 Location: Buenos Aires - Argentina Posts: 1,545
Grasping the basics

Yes Ron, I was suggested to do a FFT exactly on that. It is clear for me now.

Good Luck, thanks for your reply as well! Have to experiment with all that.
__________________
Agustín Tomás

In theory, there is no difference between theory and practice. In practice, however, there is

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