How Orthogonal Routing Reduces Crosstalk in PCB Stackups — Transcript

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1. 0:00Now this purple line and this orange line being  routed together in parallel like this creates
2. 0:05what's called broadside coupling and that's  because you have the wide portions of the traces
3. 0:10almost overlapping each other and that creates  higher capacitance between them than if you were
4. 0:15to route them side by side on the same layer Now  broadside coupling has the potential to create
5. 0:19a lot of crosstalk compared to 2 traces on the  same layer or compared to coplanar coupling So
6. 0:25here because we have a larger distance between the  2 signal lines in this case we have 45 mil for a
7. 0:3162 mil thick stackup that's going to help reduce  the broadside coupling strength And so we would
8. 0:36expect that there would be lower crosstalk between  those lines if they were carrying digital signals
9. 0:41But on a different type of board where  we might have a lot of digital signals
10. 0:44routing on these 2 internal layers in a  ground signal signal ground arrangement
11. 0:49that does create a risk of crosstalk  So to overcome that we do what's called
12. 0:53orthogonal routing and orthogonal routing  has somewhat been implemented in this design
13. 0:59The reason we do that orthogonal routing  is to minimize the overlap between those
14. 1:04traces and minimize the broadside coupling  and that minimizes the risk of crosstalk