A issue about AD9888 operation


    I am working with the AD9888 chip to capture VGA images. The resolution of the VGA image is 1280*1024 at 60 fps.  In room temperature, the output image displays normally, but when the temperature is below zero, -20 degree etc. , the output image displays with some jitter horizontally.  Does the AD9888 chip  work not well when temperature is below zero or some issues exist in my design?  

    Best regards,

    Daniel SHI

  • 0
    •  Analog Employees 
    •  Super User 
    on Mar 24, 2017 4:42 PM

    Change the PLL Filter cap materials to NPO(C0G).  X7R material caps have very poor temperature coefficients.  What you are probably seeing is the filter going out of spec at -20C.  Same issue might occur at high temperatures.  They will not be 0.0039uF and 0.039uF at the corner temps.

    At corner temperatures you need to look at temperature coefficients of all your caps that are part of the signal chain.  Also might need to look at the analog input 47nF decoupling caps.

  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:46 PM
    This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

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    EZ Admin