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Help with AD9851

Question asked by liuyang858 on Jul 22, 2015
Latest reply on Jul 22, 2015 by LouijieC

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.

 

dds_pic.JPG

 

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.

100khz_ad9851_raw.jpg

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