ADF7021 image rejection

Document created by analog-archivist Employee on Feb 23, 2016Last modified by analog-archivist Employee on Aug 10, 2016
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I found on Internet a preliminary Application Note about the calibration of the
image frequency rejection filter of the ADF7021. But I heard that you have now
a final Application Note with more details but I haven't found it on your
website. As I'm currently struggling with this calibration, could you please
send me the more complete Application Note you have available about the
calibration of the IF rejection filter of the ADF7021?

 

We do have an updated IR Cal appnote currently being reviewed internally. The
behavior mentioned below is discussed in the appnote. The reason this occurs is
because you are using Gain mode as set by Reg5_DB[31]. The results wrap around
in this mode resulting in multiple nulls over 63*31=1953 points. Gain mode
should be used which results in a single null over 31*31=961 points.

This is also discussed on page 2 of the attached PDF which you should have. In
Attenuate mode only 4 bits are swept in Reg5_DB[25:29].

I expect to release the new appnote soon.

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