Sorry if this is an ignorant question.
But I just can't fathom what the advantages are of using a differential
pair for signals not leaving the PCB.
I mean, the usual argument for using a differential pair is to increase common mode noise immunity, which makes a lot of sense in cables and connections off the board due to all kinds of common mode noise that can exist in such environments. I just don't see the big advantage if the signal begins and ends on the same board. For instance, noise from adjacent traces couples asymmetrically to the pair, and one can probably say the same for broadside coupled traces. This obviously introduces noise in the differential signal. So why not just use a single ended signal and then increase the minimum distance to other traces if one wants less crosstalk?
Electronic – What’s the point of board-internal differential pairs
crosstalkdifferentialdigital-communicationshigh speedpcb
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Best Answer
A trace on a board may also be subject to radiated signals coming from elsewhere. A differential pair will likely pick up less cross talk from such sources.
A board may be part of a system that is subject to regulations that limit the radiation it is allowed to produce. A differential pair will likely produce less emissions.
A differential receiver will be less impacted by the receiver's reference level shifting due to power supply noise or ground voltage variation.