I am wondering how I could test LVDS signals on a PCB using a scope. The most straight forward answer would be to measure on the termination resistor points, although this isn't possible, since the resistors are build into the receiver. It's also not possible to test on the pins themselves as they are placed under the chip (BGA/LGA).

At page 14 from a TI document I see that they strongly suggest not to put probes or testpoints on LVDS traces. How can you verify the integrity of the signal besides designing the trace paths accordingly?

  • \$\begingroup\$ This requires a FET buffered 0.5pFdiff. probe not a 12 pF 10:1 probe Consider that 0.5pF is 300 Ohms reactive @ 1Ghz on a 100 ohm differential line , so it will cause some reflections. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 27 at 16:06
  • \$\begingroup\$ The TI document says: "Do not place probe or test points on any LVDS traces" This is a little extreme IMO. They have probably found that people don't know how to add a probe point without making a stub. Unless I was really pushing the technology limit with high frequencies, I would always insist on probe points for troubleshooting. If your traces are already on the surface, putting a bump in the trace for a probe point won't hurt the transmission line much. If your traces are on inner layers, you will need to decide if the test point is worth the risk. \$\endgroup\$ – Mattman944 May 27 at 16:06
  • \$\begingroup\$ ti.com/lit/an/slyt163/slyt163.pdf \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 May 27 at 16:17
  • \$\begingroup\$ Would it be a bad practice to run a trace through a testpoint with the dimensions of the trace? \$\endgroup\$ – FPSUsername May 28 at 11:56

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