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Analog Verification >> Analog Performance Verification >> Theoretical noise floor in FFT
https://designers-guide.org/forum/YaBB.pl?num=1319887422

Message started by yvkrishna on Oct 29^th, 2011, 4:23am

Title: Theoretical noise floor in FFT
Post by yvkrishna on Oct 29^th, 2011, 4:23am

Hi all,

I happen to see this expression for Average FFT noise floor in many Application Notes.
----------
Average FFT Noise Floor (dB) = 6.02n + 1.76dB + 10 log(3*M / (pi * ENBW)),
where M is the number of data points in the FFT.
ENBW is the equivalent noise bandwidth of the window function (see next section on how FFTs are generated)
n is the number of bits of the A/D converter
----------

Please help me in finding a reference for deriving this expression.

Thanks,
yvkrishna

Title: Re: Theoretical noise floor in FFT
Post by loose-electron on Oct 29^th, 2011, 5:53pm

Waving the magical Google wand....

www.analog.com/static/imported-files/tutorials/MT-001.pdf

Seems to all be there.

Title: Re: Theoretical noise floor in FFT
Post by yvkrishna on Nov 4^th, 2011, 1:28pm

thanks loose-electron.

Title: Re: Theoretical noise floor in FFT
Post by loose-electron on Nov 5^th, 2011, 1:07pm

no problem -

I frequently find more useful information in application notes from vendors than from the IEEE