Common mode, differential mode

✎ This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Theoretical side

Common mode

Common mode signalling points at a situation where you have

a reference conductor, which both ends of this communication have in common

often called "signal common".

a conductor for a signal

And the signal is the voltage difference between the two.

Differential mode / differential signalling

✎ This article/section is a stub — some half-sorted notes, not necessarily checked, not necessarily correct. Feel free to ignore, or tell me about it.

Single ended

Single-ended signalling basically means all the signal is on one wire, none on any other.(verify)

A lot of the time, single-ended is used as a near-synonym for common mode.

And fair enough, common mode basically implies single ended, in that there is typically a signal common, used as a reference for one or more signals, which is usually tied to some fixed level (like ground).

Yet single-ended does not necessarily imply common-mode reference. While introductions to XLR make a big kerfuffle over sending signal/2 and -signal/2 on the two wires, it is entirely valid to send the signal on one wire and nothing on the other (which you'd easily call signle-ended), because after differential interpretation this implies the same signal at the other end and the same amount of noise reduction.

In fact, doing this is moderately common(verify) because it is a little simpler component-wise.

If a distinction is made between single ended and common mode, single-ended often refers more to the concept, common mode more to electrical reality of conductors.

Common mode, differential mode

Contents

Theoretical side

Common mode

Differential mode / differential signalling

Single ended

Derived and related terms

Practical side

Balanced audio / pro audio

Comparisons

See also

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