I'm not sure what's the reason behind this. I did notice that in the datasheet, they didn't mention a clock rate of 40 MSPS, so I'm not sure if that's the reason behind the problem. To see the datasheet, you can visit the link: https://www.ti.com/lit/ds/symlink/dac902.pdf?ts=1603505920654&ref_url=https%253A%252F%252Fwww.google.com%252F
Below is a picture of the schematics:
Can anyone give me any suggestions?