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ad9361 filter design wizard: understanding Tx Fcutoff (analog)

Question asked by obenj on Jun 12, 2015
Latest reply on Jun 12, 2015 by obenj

Hello, I'm trying to understand the 'Fcutoff (analog)' field in the AD9361/AD9364 Filter Design Wizard. I generated an example filter and attached screenshots of the filter wizard and the "Deeper Analysis" magnitude response to explain my question.

 

Based on the selection of 165 KHz and looking the 3dB drop at ~165KHz in the magnitude response, I interpret this field to be the "Tx BB LPF" from the reference manual (ug-570). Would the appropriate usage of this field would be to divide it by 1.6 to find the "BBBW" used throughout the reference manual and the Linux IIO driver?

 

I am not sure I understand the Fcutoff (analog) field correctly, since the reference manual says that the Tx BB LPF is programmable over 0.625 to 32 MHz, but my example filter is setting the Fcutoff (analog) to 0.165 MHz. How is this allowed/possible?

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