Layout of differential line

On Wed, 23 Mar 2011, Eli Gabbai wrote:

> New question #150142 on KiCad:
> https://answers.launchpad.net/kicad/+question/150142
>
> There is possibility to layout differential lines.
>
> Both lines layout together and the length of both lines are always the same.

Sorry but at the moment there is no automatic facility for differential
signal (or controlled impedence routing, since most of the issues are
similar).

You could define a custom class to mantain the correct distance but
that's all...

--
Lorenzo Marcantonio
Logos Srl

I would say that lack of differential signal/ controlled impedance routing is the most limiting factor of Kicad. Is this on the development path? How difficult would this functionality be to implement? Many thanks.

Regards,

Bernard Barker

Independent Electronics Design Consultant

www.bernardbarker.co.uk

On 03/26/2012 07:25 AM, Bernard Barker wrote:
> Question #150142 on KiCad changed:
> https://answers.launchpad.net/kicad/+question/150142
>
> Bernard Barker requested more information:
> I would say that lack of differential signal/ controlled impedance
> routing is the most limiting factor of Kicad. Is this on the development
> path?

I do not believe so, not within eyesight of the top of a priority list.

> How difficult would this functionality be to implement?

I would say weeks, not days. What some have done as a workaround, quite successfully is
do the math on the spacing and trace thickness figuring in copper thickness and layer.
Maybe using some calculator, KiCad's pcb_calc may work, haven't used it yet.

Then create a footprint with two simple round pads on it, spaced at a distance you
calculated, with diameters matching the trace thickness. Then put that at various places
along the route, and route to those pads with straight segments. You change the
orientation of the footprint at various places.

Search for a discussion Brian Buldulock and I had about it on the developer's mailing list
for a better discussion, or ask him directly there.