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I have a board which has a dual 0.1 inch header footprint (the totally standard kind you see everywhere). Trouble is, this carries a fast 300-500 Mbit DDR LVDS signal (!!) to another board. Okay, so not the best use of a 0.1 header there. I didn't make this but would like to reuse it since the board is cheap and readily available.

So: I'd like some way to carry high speed signals with some degree of signal integrity starting from a 0.1 inch header footprint. This isn't a request for a part recommendation, rather a question about how to approach this. For example I could use super-short pogo pins, or a shielded ribbon, or FPC cable, or maybe solder a single header strip to both boards directly (~3mm mated height, permanent), or maybe there is a high speed connector that fits this footprint. I can design the other board this would connect to however I want. Also, I don't need to cover any distance, this can be as short/direct as physically possible.

Btw: The differential pairs go to side by side pins on the header, and they are quite well length matched. So there is that at least.

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  • \$\begingroup\$ Are there GND pins between the pairs? \$\endgroup\$ – Simon Richter Sep 23 '18 at 5:15
  • \$\begingroup\$ Not so good, but lvds may survive. Do your best to match lines and keep impedance constant, with no vias close to pairs, except stitching vias- 10mm away. \$\endgroup\$ – Gregory Kornblum Sep 23 '18 at 5:36
  • \$\begingroup\$ @SimonRichter No grounds in between... Just at both ends of a 32x2 ;) \$\endgroup\$ – Alex I Sep 23 '18 at 8:19
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Regular desktop PC mainboards use 2x5 0.100" headers to transmit high-speed USB 2.0 signals (480 Mpbs) for ages. The only thing they use a standard twin-axial USB cable, hand soldered.

If you want to use FPC cable (0.050" wire pitch), it also works fine with LVDS over reasonable distances (15-20 cm), but you need to use header's pinout that provides the flat ribbon signals in differential pairs, like ...(G)(P)(N)(G)..., the 0.050" FPS cable will provide about 110-120 Ohms differential.

With your pre-defined pinout you can only have signle-ended wiring ...(G)(P)(G)(N)(G)... if you have properly placed grounds on your connector. Still you might have reasonable diff impedance. There are also FPC cables with twisted pairs, they also should be fine for 500 Mbps signaling.

There used to be PATA-133 connectors with ribbon cable 0.025" pitch, but they use a special metal insert and need a special pinout. I had good results with 0.025" FPC for USB 3.0 (5 Gbps) signaling up to 15 cm link.

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