What are differential pairs in PCB design?

What are differential pairs in PCB design?

Differential pair PCB routing is a design technique employed to create a balanced transmission system able to carry differential (equal and opposite) signals across a printed circuit board. Typically this differential routing will interface to an external differential transmission system, such as a connector and cable.

When would you use a differential pair?

The main reason differential pairs are used in long links that might cross between two boards is their immunity to ground offsets. A ground offset at AC or DC can be thought of as common-mode noise; it is a disturbance in the signal that affects each side of the pair in the same phase and magnitude.

How do you make xSignals in Altium?

Select the source component, then right-click on the selected component and choose the xSignal » Create xSignals between Components command from the context menu. The Create xSignals Between Components dialog will open, with the chosen source component selected.

How do you define a differential pair in Altium schematics?

Differential pairs are defined on the schematic by placing a Differential Pair directive (Place » Directives) on each of the nets in the pair. Note that the net pair must be named with net label suffixes of _N and _P. Differential pair definitions are transferred to the PCB during design synchronization.

Does differential signal need ground?

Usually, the differential signals, which are equal and opposite, do not require a ground as the return path. When the net current in differential pairs equals zero, the signal traveling through one trace returns through the other trace, which serves as the differential signal return path.

What is fly by topology?

The Fly-by topology generally connects the DRAM chips on the memory module in a series, and at the end of the linear connection is a grounded termination point that absorbs residual signals, to prevent them from being reflected back along the bus.