Tips for Cross talk Reduction

Tips for Cross talk Reduction

1. Give preference to stripline over microstrip when routing critical signals sensitive to cross talk.
2. Reduce the separation between the signal and ground layers as far as possible while still achieving the required impedance.
3. Space out the critical high speed traces as much as possible. A minimum spacing of twice the signal width is a good number.
4. Pay special attention to high speed clock signals. Keep other traces away from clock signals.
5. Use guard traces if the very high immunity to noise is required.
6. If guard trace is used, use vias to connect the guard trace to ground.
7. For traces running in parallel, the cross talk level increases with the increase in length of parallelism. The near end crosstalk or NEXT saturates after a certain length (depending upon the rise time of the signal) and the cross talk does not increase further. There is no gain in trying to minimize the length of parallelism beyond the critical length.
8. Make sure traces in adjacent layers run perpendicular to each other.
9. Add thicker soldermask on the top and bottom layer.
10. Use lower dielectric constant material. The lower dielectric constant reduces the separation between the signal and the return plane, thereby reducing the crosstalk.
11. Use a design with lower characteristic impedance.



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