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Result of FFT near DC of AD9652

Question asked by Mochi on Oct 18, 2017
Latest reply on Nov 16, 2017 by Mochi

My customers are evaluating the evaluation board of the AD9652.

My customer says;
When looking at the result of FFT near DC when there is no input, the level rises from DC to 15kHz.
I can not judge whether this is the influence of the frequency characteristic of the window function or actually there is noise.

The curve in the graph transitions from 100kHz to about 15kHz at -110dB, then uniquely rises and reaches -50dB at DC.

Is this a DC offset?
How does the expert judge this?

If there is a window function the customer should choose, please tell me with the data.
If you have NSD data near DC of AD9652, I would appreciate it if you show me.

Best regards

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