I am new with differential pair. I make a usb connection and I have to cross pairs to connect to the controller. What is the best solution? I need 90ohms impedance on 2layers, 1.6mm for the PCB.
Thanks a lot
You might want to ask yourself two questions first before looking into diff pair:
How long are your traces (worst case)? What USB standard? It might just be the case that you can ignore all diff pair stuff if your data rate is not too high and your traces are not that long.
Look for example into this old thread handling the exact same topic for guidance: Questions regarding impedance matching of USB
maybe 10-15mm for that version of the pcb.
With such long USB connections I’ve never bothered about track impedance. I only tried to make both wires the same lenght. But I have never had in mind USB3.
I will try like you said and short as possible.
It really doesn’t matter. You have allowed mismatch for USB2.0 of something like 2 cm.
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