While routing differential traces, the following points need to be considered for good EMC and Signal Integrity performance. Any compromise on these points should be avoided and enough care should be taken to make sure the differential routing rules stay as a priority. This is very much required because the differential signals typically carry very high frequency signals and any minor mismatch between the traces can be very destructive.

• The traces should be of equal length (and as a result we have no impedance discontinuities).
• Route differential traces closely together.
• The separation between the two traces (of the differential pair) must remain constant over the entire length.
• The Differential Impedance of each trace should be matched to half of the impedance of the termination resistor used.
• A Solid ground plane below the differential Signals should be provided to reduce the current loops and hence the emissions.