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TDP142: TDP142 noise

Tsvetomir Asenov
Prodigy 150 points
Part Number: TDP142

Tool/software:

Hello, 
I am using TDP142 linear redriver in my application. 
I use display port of my NVIDIA Video card, as a video source for my DP to eDP converter board to stream a 4K UHD video to a monitor. 

So far If I use Display port Cable from the NVDIA Source to the Sink that is the input of my PCB converter, using a redriver and providing the video to the display works smoothly. 

For some applications I am needing Display port cable attached to NVIDIA and then I have male to female DP and then the rest of the circuit is the same as the one I mentioned.

The main difference is that I am using different cable: Male connector to the DP source which ends with Male connector. The second cable is Female DP connector to Male DP connector and then it goes to the converter board. 

The problem is when I use two cables with Male to Female connection in between, from some time I am getting a bit of a noise in the video streaming that can be senses looking at the monitor. 

If I use just straight connection between DP source and DP sing, no issue are observed. This is only In case I use one male to male DP connector. 
Otherwise if I use two cables, noise is present. 

How can I fix it? 

Thanks!

  • 0
    TI__Mastermind 21285 points

    Are there any differences in cable length/ are you able to send a block diagram of your setup? I'm having a little difficulty visualizing the setup. 

  • 0 in reply to Vishesh Pithadiya
    Prodigy 150 points

    Hello, 
    Yes! 

    This is the setup.
     

    If I only use Male to Male DP connector between the PC and the DP to eDP PCB converter board, then the video is fine and no noise is present. 
    But If I use Male to Male and then Female to Male cables then a bit of noise is present. 
    I tried different attenuation settings of the TDP142 but it does not help. 

    In  case when I use Male to Male and then Female to Male cables the total length of the cable is not larger than the length of the cable when I use Male to Male DP cable. 

  • 0 in reply to Tsvetomir Asenov
    TI__Mastermind 21285 points

    Hey Tsvertomir,

    Thanks for the visual, it helps a lot.

    The reason you see some noise when using the x meter MM -> x meter FM cable and not when just suing the 2x meter MM cable is because when using the two sets of cables creates the same length of 2x, but with 4 connectors. Having this many connectors in the signal path will add additional reflections and ISI which you are seeing with the noise on the display. 

    One option is you can try increasing the EQ value when using the two cables to see if that improves the signal quality.  

  • 0 in reply to Vishesh Pithadiya
    Prodigy 150 points

    Hello Vishesh, 
    Thanks for the valuable information!

    I've tried several different settings, even the maximum settings for the EQs and there is no difference that can be sensed! 
    I will try with higher quality cables! 

    Thanks! 

  • 0 in reply to Tsvetomir Asenov
    TI__Mastermind 21285 points

    Sounds good, let me know if you have any more questions!