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AD8293G80/AD8293G160 Overall Bandwidth

Question asked by mathew on Aug 29, 2017
Latest reply on Aug 31, 2017 by mathew

Hi,

 

The datasheet for AD8293G160 shows how two 700Hz filters are used in conjunction to form a 500Hz bandwidth.

 

For my application, I will be sampling at 200Hz and a would like to filter out (most) frequencies above 67.7Hz. I plan to use the recommended 680pF capacitor between FILT and OUT (C2) to create a 700Hz primary filter and to use a 0.47uF capacitor on ADC OUT (C3) to create a 67.7Hz secondary filter (which will be used as an ADC anti-aliasing filter).

 

1) What is the overall bandwidth with a 700Hz primary filter and a 67.7Hz secondary filter?

2) Is this the recommended approach to achieve a cut-off frequency around 67.7Hz (for anti-aliasing)? Or would it be better to achieve the same overall bandwidth by reducing both the primary and secondary filters from 700Hz to e.g. 200Hz?

 

Many thanks in advance for any assistance.

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