why noise often measure in Square(RMS)

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sys_eng

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I can understand RMS is like the average, not the instaneous value.
but why sqaure it? why not just plain RMS. or to 3rd, 4th power.
why square?
 

The definition of "plain" RMS is the square-root of the sum of the squares.
That gives the equivalent power value of the waveform (normally used in signal analysis), which is why the square is used (since power is proportional to the square of the voltage).
It's not the average value.
Does that answer your question?
 

Hi,

Maybe you mean thenoise given at Opamp.
Like noise: 8 uV/sqrt(Hz)

This is not an absolute value of noise, but the noise_density....along the frequency axis.

To calculate the absolute value of noise you need lower and upper freqency limit (of interest).

Read: Noise Calculations1 in Op Amp Circuits – Design Note 15 from Linear Tecnology

Klaus
 


why 8 uV/sqrt(Hz)? why not 8 uV/(Hz)?

and Equivalent input noise=9.23 μV or 20.64 nV/√Hz
why those two the same?
 
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