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Re: Trace length tuning/matching for Kicad

 

Here is a 100 mbaud ethernet switch I did 2 months ago, 5 ports, 10 length matched
differential pairs.

The RXP1 and TXP1 traces go a little out of their way as they begin, this is so they match
the RXM1 and TXP1 traces in length, respectively.

In this case 45 degree delays were enough, along with the "drag and keep parallel" capability.


100 mbaud ethernet is fairly tolerant, when you consider that an ethernet cable is
essentially a continuation of this path, albeit on the other side of a 1:1 transformer.

So with all the imperfections in the .1-100 meter cabling, having a small delta on the
board won't kill you at 100 mbaud.  But if you don't do it and it doesn't work, who you
gonna blame?




Attachment: length-matched.png
Description: PNG image


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