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I have seen many applications where micro-coax is used for differential signals. For example display panels with LVDS or eDP, and a I-PEX VS type connector. The I-PEX connector even names USB4, HDMI etc. in its applications.

But how do you get the right differential impedance, if you run each of the signals in a separate coaxial cable?

While doing some research I came across the term twinax, which is coax with dual inner conductors. Is that what is usually used, or can you run a differential signal in two coaxial cables?

I found this "Micro coaxial Connectors Handbook" stating for example LVDS as typical use case for micro-coaxial cable. enter image description here

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    \$\begingroup\$ Please add a schematic of an example you have seen. \$\endgroup\$
    – Andy aka
    Commented Jan 3, 2022 at 17:58
  • \$\begingroup\$ @Andyaka I have no examples with full schematics, but I added one more place I have found that mentions LVDS to be used with micro-coax. I have some display datasheets using this type of connector, but they are under NDA. But it seems to be pretty much standard when looking at cable manufacturers for I-PEX VS and similar connectors, that they advertise micro-coax for all types of applications with high-speed differential signals. \$\endgroup\$
    – Klas-Kenny
    Commented Jan 3, 2022 at 18:28
  • \$\begingroup\$ You can use two 50 ohm single ended coaxial cables for single 100 ohm differential signal, unless there is something special that prevents it. Can you be more specific if this answers your question already or is there something that needs clarification? \$\endgroup\$
    – Justme
    Commented Jan 3, 2022 at 18:30
  • \$\begingroup\$ @Klas-Kenny But how do you get the right differential impedance, if you run each of the signals in a separate coaxial cable? - how could it not be the right impedance? Where are you having difficulties with this concept? In the absence of a tangible example, this comment returns to you to justify your problem. \$\endgroup\$
    – Andy aka
    Commented Jan 3, 2022 at 18:32
  • \$\begingroup\$ @Andyaka Well, afaik the impedance is depending on the ratio of capacitance and inductance between the two conductors. So if these two conductors are completely shielded from each other, I don't know what happens to the impedance. I could guess that the two 50 Ω to ground in "series" will result in 100 Ω differential impedance ("throug" the ground?), but I want to know, not guess. Preferably citing some trustworthy source or at least a good explanation. \$\endgroup\$
    – Klas-Kenny
    Commented Jan 3, 2022 at 18:37

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