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AD9380 component interference issue

Question asked by cjameshuff on Jul 29, 2011
Latest reply on Aug 2, 2011 by cjameshuff

We're seeing a faint 1-pixel pattern of alternating light and dark vertical lines in on 720p video using component input 0 and YCbCr 4:2:2 output. I suspect interference from the CbCr bus is getting into the analog inputs, causing these lines to appear on colors where the digital Cb and Cr codes are different in a large number of bits. Simply touching the pins on the CbCr bus clears the problem up, and putting a heatsink or copper tape on the IC also improves things. (The effect is immediate on placement or removal of the heat sink...it's not thermal, but seems to be due to added capacitance.)

 

We do not have series resistors on the digital bus, but an evaluation board with the same part does have them, and exhibits the exact same problem.

 

Has this problem been encountered before by anyone, and does anyone have suggestions on how to fix the problem?

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