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about ad9920a  black clamp

we are using ad9920a+kai-02150.the left and right edge (about 100 pixel) of the image are more bright than the center part under low-light scene. we disable the clpob. when we set the clamp level to 0,the phenomenon is weak,to 3ff obvious.  the hardware or the setting of ad9920 is not right? who can give some advice and explanation about the black clamp of the AD9920A?

I am forwarding this to the AD9920A expert.

  • when we change the camera to one-tap-out(one channel) mode, the bright-edge phenomenon does not exist.

  • Can you please confirm the clamp setting used during the problem condition- is the clamp enabled or disabled for these plots?

  • the setting are

    LineHDLEN
    =1546
    LineHBLKSTART =80
    LineHBLKEND =596
    LineVSTARTA =0
    LineVLENA
    =288
    LineCLPOBTOG1 =608
    LineCLPOBTOG2 =628
    FrameHDLEN =1546
    FrameHBLKSTART =80
    FrameHBLKEND =888
    FrameVSTARTA =0
    FrameVLENA
    =800
    FrameCLPOBTOG1 =8191
    FrameCLPOBTOG2 =8191
    LineLength
    =1546
    LastLine
    =1838
    CCDLineLength =1014
    CCDTotalLines =1152
    ES_START_PIXEL =80
    ES_END_PIXEL =120
    PBLK_START =8191
    PBLK_END =8191
  • What is the setting of register 0x00 bit [2] (clampenable) when you see the issue?

    Since you have a condition that does not show the issue (dual tap mode) we need to understand better the differences between these two conditions (dual tap vs. single tap). It is possible the single tap timing patterns for the CCD are not correct, or maybe the clamp pulse position is not correct. But, if the clamp is disabled for all of your measurements, the clamp position does not matter.

  • single-tap mode works well,two-tap mode bad. whether clamp enable or disable ,the issure always can be seen. can you provide us the setting of two-tap pattern?

  • It sounds like the CCD timing settings could be incorrect, because the AFE is operating correctly in single-tap mode. I suggest you double-check the CCD timing patterns for dual tap mode.

  • 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.

    Thank you,
    EZ Admin