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Does accuracy matter with AD7745/AD7747 when looking only for changes?

Question asked by jchang16 on Jan 21, 2016
Latest reply on Jan 29, 2016 by Wa$iM



I have a very small capacitive proximity sensor that has a total capacitance of <2fF and I want to be able to track its change in capacitance.  I have plugged it into a AD7747 eval board and I'm seeing capacitance changes on the order of tens of aF in response to proximity changes.  The capacitance changes seem to be correlated with the proximity changes but with the accuracy of the AD7747 stated as 10fF, can I trust the data?  I don't really care for the true capacitance reading since I only care about its change from baseline.  Does that mean that I don't need to be concerned about the 10fF accuracy?


Thank you,