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I was reading this article on common mode and differential mode noise.

But it is not mentioned anywhere on how the differential mode noise and common mode noise occurs.

From the diagram, I kind of understand like, due to the stray capacitance and parasitics, the common mode noise occurs. But what is the reason for the differential mode noise? How does it occur?

It would be really helpful for me if one could draw up the noise waveform on both the (+ve and return path) for the differential mode noise.

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  • \$\begingroup\$ Are you in fact asking how noise (or interference) occurs? \$\endgroup\$
    – Andy aka
    Jun 23, 2021 at 7:15
  • \$\begingroup\$ Like, what causes these noises? Differential mode noises \$\endgroup\$
    – user220456
    Jun 23, 2021 at 7:18
  • \$\begingroup\$ How is a (differential) signal generated? It might be a signal from a sensor which has been amplified. The sensor and the amplifier both add noise to the signal that you want to measure. That noise will be differential noise as it is added to the differential signal. \$\endgroup\$ Jun 23, 2021 at 7:31
  • \$\begingroup\$ So, will the differential noise waveform be same on both the lines of the differential signal or will it be opposite? \$\endgroup\$
    – user220456
    Jun 23, 2021 at 7:54
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    \$\begingroup\$ will the differential noise waveform be same on both the lines of the differential signal or will it be opposite? You need to think and realize that signal and noise are treated in the same way. If we were talking about a signal instead of noise, would the polarity of a differential signal be opposite or not? Now consider that the same applies to noise as well. \$\endgroup\$ Jun 23, 2021 at 9:38

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There you go, imagine the sources as noise injection.

schematic

simulate this circuit – Schematic created using CircuitLab

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