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AD5933 Capacitance Measurement Optimal Calibration Topology

Question asked by leviathan on Feb 26, 2018
Latest reply on Feb 26, 2018 by Snorlax



I'm trying to make a high accuracy capacitance measurement circuit (range 300pF - 2000pF). And I wanted to know what type of impedance circuit for the calibration (R_cal). 


In the datasheet for AD5933 and CN-0217, most of the examples given use a purely resistive calibration impedance. However, on the EVAL Board document (UG-364), it mentions that the topology of the calibration impedance depends on the application. 


Can someone please describe what factors should be taken into account when deciding the topology, and perhaps the best topology for an application that measures capacitance.


Thank you in advance for any help