How do you place components for differential pairs?

[crgarcia]

Hi,
When you try to do differential pairs, components need to be place very accurately. How do you do that? it usually takes me a very long time, and some times I cannot even do that. For example:

I would like to route that straight up, and move the component if needed. Instead kicad will try to do a weird route because the component is not super-perfectly aligned

How do you handle these situations?

[Piotr]

@crgarcia

How do you handle these situations?

I didn’t used differential pair but just counted each connection length and summed them in spreadsheet.
I decided that I need paired the length from beginning to end with don’t care where the intermediate points are. Here is my solution (I don’t know if it is perfect):

The pairs are from socket pins 1,2 and 3,6.

[eelik]

What’s your KiCad version?

[crgarcia]

version 6. I also used v5 but I have the same problem. I guess people do it differently than me, because it is very time consuming to route this.

[der.ule]

When I do differential pair in KiCad, I don’t do it “point-to-point”, with this I mean, I do not click in a pair of pads and then click on the other pair of pads, this ways, the tracks are almost always a mess.

What works for me is to use some intermediate points:

1. I click in the first pair of pads, then I “choose” the way I want the DP to exits this pads by moving the mouse around, when I am satisfied, I click to ‘fix’ that segment and start working in the next segment, in this case the straight line between the two components.

2. I move the mouse until I am close to the target component (not too close otherwise it will be difficult to achieve a connection) and click again to ‘fix’ the segment I just laid.

3. From my last segment I try to connect to the second component’s pads, if I am satisfied with the result, then I am done, if not I can delete only the last segment, reposition the second component and try again.

4. Sometimes it is easier to get a good result if you do steps 1 & 2, but instead of continue until the target’s pads, you start your last segment from the pads of the second component and then connect to the your already routed segments.

Unfortunately, I’ve realize that the shove or walk around modes from the interactive router are not good for DP (at least, they normally mess up what I am trying to do), hence for doing DP I set the mode to “signal collisions”.

I hope this helps.

EDIT: Do not forget to choose a suitable small (but not too small) grid for doing DP, it makes everything easier.

[Lutz_Muller]

The way I do it is that I first count all the lines and add the two most to the front and back as a filled area.
Then a DRC check and then the remaining routes.

Electric continuity tester