Crosstalk Prevention: Using the 3W Rule for Trace Spacing

Crosstalk is degradation of signal quality that occurs between traces which are close to one another. The 3W Rule is simply to keep at least three times the width (W) of the trace separation between parallel traces will eliminate, or greatly reduce, the effect of electromagnetic coupling, thereby reducing the interference which can be experienced in most digital designs. For high-speed and highly sensitive analog signals, even larger distances or use of shielding techniques (i.e., ground traces or ground planes) may be necessary. It is very important to route all critical signal lines over continuous reference planes and try to avoid long parallel runs. Following the 3W Rule early in the design will help to ensure that the signal integrity will be retained without requiring complex redesigns later.

PCB with crosstalk prevention