AD9287 Dataout frequency not right

I  have gotten a problem with AD9287ABCPZ-100, as follows,

According to the Timing diagram of AD9287 ,when my input  clock is 20Mhz, the frequency of dataout should be 80Mhz ,and the bit clock(DCO) should be 80Mhz ,frame clock(FCO) should be 20Mhz .

But in fact ,the frequency of DCO and DCO is right ,but the frequence of dataout is 20Mhz,too. So it makes me confused ,Idont know which question leads to this. SO I need a help.

Thanks for your answer !

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    •  Analog Employees 
    on Apr 2, 2019 3:21 PM over 1 year ago in reply to XIAWEN

    Hi Xiawen,

    A negative differential voltage (voltage on D+A - D-A --> negative) on the LVDS outputs corresponds to a logic 0 value. This sounds like a reasonable static value. I do not know the state of the ADC when you are taking that measurement but logic 0 output does not necessarily indicate any kind of problem.

    Doug

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