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AD9779A emissions issue

Question asked by tmain on Oct 13, 2014
Latest reply on Oct 13, 2014 by YiZ

I’m running 160MHz in to REFCLK and configured the part to bypass its PLL, so internal DACCLK runs at 160MHz.

I’m seeing a large 320MHz RF Emissions from the AD9779(A) part, which is causing my product to fail FCC. (See attached, measured with sniffer probe over PLL corner of part.)

When I change my configuration to use the PLL and run DACCLK at 320MHz, the emissions moves to 640MHz.


Are you aware of any known RF emissions issues for the AD9779(A)?

Or might you know what in the AD9779 could be emitting at twice the DACCLK frequency? (So maybe I could reconfigure part to minimize emissions.)