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I am using twisted pair cable for LVDS communication between the Host and the display. It was recommended that the differential impedance of cable should be 100ohm (+/-5%).

Let me know how to measure and verify the differential impedance of a twisted pair cable before using it in any system. I want to do only in cable level by not connecting it with host and display.

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  • \$\begingroup\$ Do you have a pulse generator and an oscilloscope? \$\endgroup\$ – Andy aka Jul 27 '15 at 14:37
  • \$\begingroup\$ Connect it to a similar signal driver and receiver and see what termination resistances make the waveform the prettiest. Or just hook it up to an impedance analyzer. \$\endgroup\$ – Spehro Pefhany Jul 27 '15 at 17:03
  • \$\begingroup\$ @ Andy: yes, i do have an oscilloscope and fg. \$\endgroup\$ – V V Rao Jul 28 '15 at 4:53
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First, note that we're talking impedance, rather than resistance, so you can't just put an ohm meter on it to check.

Differential impedance will depend to some degree on frequency, so it's necessary to measure at the frequency which you expect to encounter, and preferably higher in order to give some safety margin.

The only way to test the cable is to send an LVDS signal through it and monitor the received signal. Make sure the receiver is properly terminated, and use a signal at the same data rate which you will be using.

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