Kang, Thank you for your quick reply. I have already read the app note, it is very interesting and has a lot of good information but I don't think it answers my question. We had already tried using separate linear power supplies with no noticeable improvement but I will try using a battery. If you look at the picture the phase noise response out of the DAC3482 resembles that of a loop filter for a PLL. That is why we tried bypassing the LMK chip and disabled the PLL of the DAC3482 . I can download the registers from the DAC and send them if that would be of use. Thanks again for your assistance. Tom
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