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DS90UB913A-Q1: Jitter and LVDS measurement

user4176848
Prodigy 60 points
Part Number: DS90UB913A-Q1

Hi，

I have two question about DS90UB913A/DS90UB914A:

1>. 913A worked in pclk mode,How to make sure the parameter of tJIT0 of clock is ok or not?

Below is our measurement,can you help to confirm the result is ok or not?

MeasReport.rar

2>. How to check whether the LVDS differential signal is meet spec at receiver side?

The differential signals include forwoard and back channel at the same time. We need make sure both of the signals meet parameter of VID. 

  • 0
    TI__Genius 12866 points
    Hi,
    1. Please refer to DS90UB913A datasheet section 7.6 Recommended Serializer Timing For PCLK. The max input jitter is 0.3UI. Are you running the device in 12bit HF mode? If yes, from your result, the jitter is 0.29UI which passes the requirement. If the device is in 10 bit mode, it passes as well with better margin.

    2. When you say LVDS differential signal do you mean the FPD-LINK signal between 913 and 914?
    You could connect one end of the cable to 913 and measure at the other end to check for Forward channel VOD and compare to VID requirement on 914.
    Connect cable to 914 and measure at the other end will get you back channel VOD.


    Sincerely,
    Charley Cai
  • 0 in reply to Charley Cai
    Prodigy 60 points

    Hi Charley,

    thank you~

    1. 913A worked at 10bit mode and the pixel clock is 74.25Mhz;So, 0.3UI is about 288ps.

    But how to use below data to check whether the jitter is in or out spec?

    Measurement Results

    Description Mean Std Dev Max Min p-p Population Max-cc Min-cc
    TJ@BER1, Ch1 210.87ps 26.044ps 396.20ps 138.23ps 257.97ps 789 0.0000s 0.0000s
    Current Acquisition 217.41ps 0.0000s 217.41ps 217.41ps 0.0000s 1 0.0000s 0.0000s

     

    2.Yes,it's the differential signal between 913 and 914.I will try this again~

     

  • 0 in reply to user4176848
    TI__Genius 12866 points
    Hi,
    You are correct that 0.3UI is about 288ps.

    TJ@BER is the total jitter measured at Bit error rate. Usually we set the population to 100, in your case it stopped at 789 population which is a little too much.

    Typically with 100 population, we compare 288ps to the Max TJ@BER value to check for pass or fail.
    With the data you provided, Mean and Std Dev is low enough to pass 0.3UI which is why I said it should be ok.

    I checked provided report further, and saw that F2 has 1st order filter on. This should be a second order filter.
    You could try to change the filter setting and population and check for jitter again.

    Hope this explanation is clear.

    Sincerely,
    Charley Cai
  • 0 in reply to Charley Cai
    Prodigy 60 points
    Hi Charley,

    About diffential signal,Only the parameter of VID shows in spec,It's has eye hight and opening spec?
  • 0 in reply to user4176848
    TI__Genius 12866 points
    Hi,
    We currently don't have a suggested number for eye height and opening. Please follow jitter and VID/VOD requirement.

    Sincerely,
    Charley Cai