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Help with AD9851

liuyang858
on Jul 23, 2015

I designed and printed a PCB that takes in signals from a Raspberry Pi, uses those signals to control the AD9851, amplifies the waveform, and outputs the amplified signal. However, I'm having trouble getting the signal from the AD9851 look like what I'm expecting.

For comparison, I bought a DDS60, which seems to have a much cleaner output than mine. Does anyone know what could be the difference? I think I'm following the schematic fairly closely.

I have some images below, but let me know if more information is needed as well.

Here is my schematic.

Here is the waveform I get from the AD9851 when I try to set it to 100 khz. The same code used on the DDS60 produces a much cleaner result.

  • 0
    •  Analog Employees 
    on Jul 22, 2015 4:52 PM over 5 years ago

    Hi Lisa,

    It might be that the board is not the fault here but on how you probed it. Try probing it but with the consideration of using a ground path that is close to the tip of the needle. It might be that the measuring setup is contributing the noise and not  the board itself. You can verify this by by probing a "clean signal" and use it as basis for comparison.

    Best Regards

    Louijie

  • 0
    •  Analog Employees 
    on Aug 2, 2018 3:07 PM over 2 years ago
    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