1
\$\begingroup\$

I have 4 differential signal pairs (LVDS Data lines and Clock) running between my Microcontroller and TFT. There are no test points over the lines.

Can someone tell me what is the best practice and how to measure the differential signal LVDS Lines (Measurement of Voltage levels and timings)?

  1. Since there are no Test Points on the LVDS Lines, should I scratch the lines on the PCB vias and measure it on the PCB Vias?

  2. Should I measure near the MCU or TFT?

  3. Any resistor should I attach at the tips of the differential probe before measuring?

  4. Apart from Voltage level measurement and timings (Setup and Hold time), are there any valid test I should do to check whether my LVDS Lines are fine?

\$\endgroup\$
5
  • 1
    \$\begingroup\$ differential FET probes likely beyond your budget \$\endgroup\$ – Tony Stewart EE75 Mar 4 at 3:55
  • \$\begingroup\$ Yes, they are very expensive. Fortunately, I was able to borrow a probe from a friend of mine. \$\endgroup\$ – Newbie Mar 4 at 3:55
  • 1
    \$\begingroup\$ literature.cdn.keysight.com/litweb/pdf/5988-4797EN.pdf \$\endgroup\$ – Tony Stewart EE75 Mar 4 at 3:57
  • 2
    \$\begingroup\$ It has been a long time since I did this. You want to check signal integrity at the input of the receiver, not the output of the driver. If there is a component such as a termination resistor or capacitor, that is a good place to probe. The differential probes I have seen have two pins sticking out. Often you can touch the termination resistor with the two pins to capture the signal. Wires are your enemy. If you use wires between the signal and the probe, they should be exceptionally short. Only 10mm or less if you can manage it. \$\endgroup\$ – mkeith Mar 4 at 4:50
  • 1
    \$\begingroup\$ it depends on what you need to know about your signals. To do an eye test you'll need good probes and a good scope. To only see the bits you could probably use an MLVDS receiver and see what comes out. \$\endgroup\$ – Lorenzo Marcantonio Mar 4 at 8:50

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.