How to measure the noise voltage characteristics of this circuit?

KafenWong

How to measure the noise voltage characteristics of this circuit? [Copy link]

Can someone tell me how to choose the noise source?

My book only says that by short-circuiting the input terminal and GND, the spectrum of the noise voltage can be measured... But it does not explain how to measure it.

chunyang

General simulation cannot measure circuit noise, it must be based on the real object. For the original poster's circuit, the input is short-circuited to the ground and then the output signal is observed to obtain the background noise of the circuit. Its sources include the thermal noise of the device, that is, the change of device parameters due to temperature and the impact on the output, and the noise generated by electromagnetic radiation from spatial coupling. To remove the latter, it is necessary to test in an electromagnetic shielding room, and the test equipment itself cannot radiate external electromagnetic noise. Therefore, the conditions required for precise testing of circuit noise are very high, and the cost of investment is also very high.

The specific testing method is actually voltage testing and spectrum analysis, but the usual oscilloscopes and spectrum analyzers cannot meet the requirements and require special equipment or accessories.

KafenWong

chunyang posted on 2020-10-31 20:00 General simulation cannot measure circuit noise, it must be based on the real object. For the original poster's circuit, short-circuit the input to the ground and then observe the output signal to get the circuit's...

That's how it is. Thank you.