4.4 Avoiding Crosstalk
Crosstalk is defined as interference from one trace to another by either or both inductive and capacitive coupling. Best ways to avoid crosstalk are:
- Provide stable reference planes for all high speed signals (as noted in previous sections).
- Use the 3W rule (3 times the width of trace for separation) where applicable on all signals, but absolutely use on clock signals.
- Use ground traces/guards around either “victim” or “aggressor” signals prone to crosstalk.
- When constrained and space limited on areas of the PCB to route parallel buses, series and/or end termination resistors can be used to route traces closer than what is normally recommended. However, calculations and simulations must be done to validate the use of series or end termination resistors to eliminate crosstalk.