AD8476 - RC filter after the AD8476

Document created by analog-archivist Employee on Feb 23, 2016
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I would like to place an RC filter after the AD8476, but I am using a different
ADC than the one shown in the data sheet.
Can you give me a cookbook approach for what filter components to use?

 

For a typical SAR ADC, the RC filter cutoff frequency must be set high enough
so that the ADC input can settle to the ADC precision (1/2 LSB) during the
acquisition time of the ADC. Typically, the capacitor can be set to about 2nF
so that the AD8476 can drive it properly, and then the resistor can be chosen
to achieve the necessary bandwidth. Adjustments can be made from there to
achieve the best performance. For more details on the calculations involved,
refer to the following Analog Dialogue article:
http://www.analog.com/library/analogDialogue/archives/46-12/sar_front_end.pdf

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