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Accuracy of AD7746

Question asked by shrikris on Mar 27, 2016
Latest reply on Mar 28, 2016 by Wa$iM

Hello Everyone

I am using first time AD7745 for measurement volume of material. In my experiment, empty sensor capacitance is about 6pF and adding material it changes by 50fF so becomes 6.05pF.  So by subtracting 6pF from 6.05 pF, I can find change in capacitance due to addition of material in sensor.  Now my question is about repeatability in reading the same material again and again. Now from the datasheet it's mentioned that reading capacitance error of +/- 4fF means 50 fF may read as anything between 46fF to 54fF.So reading repeatedly same sample could lead to worst case error 0f+/- 8%?. Is it correct?


Thanks and Regards

Shri Kulkarni