How to test a noise level in a dc voltage?

[bluerainbow]

thanks!

 

[IanP]

You can use an oscilloscope to "see" what is the AC component (noise) on a DC line.
Adjust it to AC mode and increase its mV/div (V/div) to read noise level..

 

[bluerainbow]

If I want to examine the noise below mV such as µV,how can I do that?

Thanks.

 

[IanP]

In this case you will have to use an instrumentation amplifier of gain, say, 100, or more and then you will be in mV region, and that can be seen on a standard oscilloscope ..

 

[bluerainbow]

thanks.

In this case I have to choose a amplifier that have low offset voltage.Right?

 

[IanP]

It should have low gain error, low gain drift (ppm/°C), LOW Voltage Offset, high CMMR and wide BP .. so in other words a good instrumentation amplifier.
Some examples you can find at Analog Devices web site: https://www.analog.com/

 

[echo47]

What frequency noise are you looking for? Megahertz? Millihertz?

 

[ezpcb]

It should have low gain error, low gain drift (ppm/°C), LOW Voltage Offset, high CMMR and wide BP .. so in other words a good instrumentation amplifier.
Some examples you can find at Analog Devices web site: h**p://www.analog.com/

unfortunetly, instrumentation amplifier unually don't have high band width. Choose the right amplifier depends on the noise bandwidth you want to measure.

mike

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