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I need to use a connector that only exists in a version for PCB installation, but I have to connect it to a cable; so, I was thinking of making a small adapter PCB on which to directly solder the wires.

Now my problem is that I have to create this adapter PCB for various cables, which are all different: some are CAT5 and CAT6 Ethernet, some are LVDS signals, others are single wire signals, etc etc all with different pinouts; and I would like to make a single generic adapter that works for everyone.

My question is, since the PCB will only be a few centimeters, maximum 4 or 5 cm, can I use all straight traces not considering the differential pairs? For example, if I have an ethernet signal with differential pairs at 100ohm, if I have a piece of 4 or 5 cm in which I only have single ended traces, can I have problems?

If so, I would have all single ended tracks, and since I don't have a ground plane, I can't control the impedance of the tracks. What track size should I use to have as few problems as possible?

Thanks in advance

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  • \$\begingroup\$ What connector is this? If it's designed for board-to-board connections, it may not be the best choice for a cable-mount connector. \$\endgroup\$
    – Hearth
    Commented Oct 4, 2023 at 15:00
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    \$\begingroup\$ Why not use a ground plane and impedance match everything so that you're sure it will be ok? \$\endgroup\$
    – user1850479
    Commented Oct 4, 2023 at 15:01
  • \$\begingroup\$ @user1850479 if the PCB is a 2-layer 1.6mm FR4 then you may end up with ridiculously wide traces for the required diff impedance. For such a simple board 4-layer (or more) would be overkill. \$\endgroup\$
    – Rohat Kılıç
    Commented Oct 4, 2023 at 15:27
  • \$\begingroup\$ @RohatKılıç Unless he is doing this at home, the cost of a 4 layer, controlled impedance board this small is maybe 2 or 3 dollars extra for 5 or 10 boards. I think that is worthwhile if routing LVDS. \$\endgroup\$
    – user1850479
    Commented Oct 4, 2023 at 15:42
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    \$\begingroup\$ Usually LVDS has a ground on the connector which you would tie to the plane. If it doesn't then you could route it like Ethernet and get the target impedance by coupling the two signal lines with no ground. \$\endgroup\$
    – user1850479
    Commented Oct 5, 2023 at 14:07

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