Electronic – To find theRMS noise voltage in a circuit, can the measured RMS voltage be subtracted from the RMS voltage of shorted probes

analogmeasurementoscilloscopeprobesnr

I'm trying to estimate the SNR of a circuit, which includes measuring the noise power of an analog trace. Right now, I'm attempting to measure the noise with a high bandwidth scope probe, ac coupled, low inductance ground leads, with 1x attenuation. However, I want to attempt to remove the RMS noise induced from the probe itself.

tldr: Is it possible to subtract the RMS noise measured with a shorted scope probe from the RMS noise measured of an analog circuit trace for a more accurate measurement of the actual RMS noise on the trace?

Best Answer

You need to subtract the squares of the RMS voltages then take the square root to obtain the noise of the source. However, this is only accurate if there is no coherence between sources.