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How is Noise of a component measured?

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aryajur

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Suppose I have a opamp IC on my bench, what instruments would I need to measure the noise spectrum of the IC. I want to understand, how does a IC manufacturing company characterize the noise performace of the IC?
I am confused on this because to plot the power spectral density we need to take the Mean square value of the noise voltage taken over a long time filtered at a 1Hz Bandwidth. How is this long time set?
 

How is Noise or a component measured?

hi, a simple way of noticing noise is by observing it on any Display, because for every device from R and C to Big chips there is an ideal curve that it must satisy ,so is you dont observe that curve a perfectly and notice some level changes ,then that can certainly conform noise. and an estimate of its noise can be done
 

I am more interested in knowing how the Noise spectrum is measured and put in datasheets?
 

This paper provides a testing procedure for measuring noise for an opamp.

fig.3 page 5

III. MEASUREMENT SYSTEM AND MEASUREMENT METHOD

**broken link removed**

It woudnt be a simple procedure the noise is small magnitude (pico/nano) and not periodic.
 

The noise is measured using an servo analyzer equipment.
The equipment will automatically convert the noise in Vrms/(Hz)1/2.
Hope this will help u.
 

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    aryajur

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There are special devices called Noise Analyzers. I am sure that you can find some info in Lecroy or Agilent/HP websites on this.

In your datasheet, you would list a RMS noise level which can be obtained from the Noise floor of a spectrum analyzer.

Importantly the probes you use and the environmental conditions like vibration and other distrubances would directly effect the noise measurements you make. The spectrum analyzer would sample the noise in a window to make it being read as periodic noise. Anyways, the measurements will be quite reliable if the test bench is untouched.
 

I think by using the averaging function of a spectrum analyzer, it should be ok...
 

jbi00b said:
I think by using the averaging function of a spectrum analyzer, it should be ok...
Click to expand...

jbi00b:
Is you means using average , then multiply sqrt(Hz) ?
 

jbi00b said:
I think by using the averaging function of a spectrum analyzer, it should be ok...
Click to expand...

We would have to average out the square of the values of the noise voltage then we will get the mean square values. I have't used a spectrum analyser, is it possible to do that?
 

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