Electronics > KiCad

KiCAD - Problem in routing Differential Traces

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Arsh ahmad:
Hi,

I am having some problems with routing differential traces in KiCAD, by using P and N notations I am able to route them like a normal single ended trace, but then how to drag them as they are dragged like a single ended trace.

Is there any work-around for this?

jduncan:
nope

Doctorandus_P:
This is also one of the oldies. It is tracked in:

https://gitlab.com/kicad/code/kicad/-/issues/2005

And no, it's not from 2005, but from 2016, which is also plenty old. KiCad development is a bit chaotic. There is some leadership and and direction, but most of the developers are volunteers, and they are free to work on any section that interests them most. And with 1500 open issues on gitlab, some of the older issues do get behind a bit, but they are not forgotten.

phil from seattle:
You don't give much info but differential traces in Kicad are very fussy and give you no feedback as to what is happening - either it works or it doesn't. There are a number of settings that affect it (from memory: board setup predefined sizes and netclasses, filled zone rules, ...)  Keep playing with it. Same thing with length tuning.  Once you get a feel for how it works, it's not too bad though.

Often the traces look really weird when routing the starting or ending points.  I sometimes fix the really ugly ones individually and then length tune when done. For length tuning, try to have lots of uncluttered space available. I usually do it very early in the layout process because of that.

Arsh ahmad:
Most of the interfaces are fine for length matching, but DDR routing requires lot of dragging and that takes lot of time, If there is any tutorial or any session for routing DDR in KiCAD it will be very helpful.
For company use I use Allegro that has very sweat length and Delay tuning utility built it into it. This is the reason whenever I have a SoC design I am not able to use KiCAD and I have a to go for Cadence(Which has advanced features but interface is worse compared to KiCAD since it is a cluttered mess).

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