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AD5933 Complex impedance measurement

Question asked by RaymondNhembo on Jun 1, 2018
Latest reply on Jun 5, 2018 by Snorlax

I am trying to measure a microfluidic circuit, a conduction circuit which can be modeled down to a CRC circuit using the AD5933 Evaluation Board. Page 8 of the Data Sheet ,the AN- 1252  states that:

 

MEASURING A COMPLEX IMPEDANCE

To measure complex impedance, refer to the conversion table (see Table 7) to calculate the maximum and minimum impedance based on the excitation frequency. This section describes three points to keep in mind.

Do Not Calibrate the System with a Complex Impedance

Otherwise, phase results will be not as expected. This is explained in the Calculating the Gain Factor section.

 

Questions:

  1. Table 7 gives schematics of such complex impedance examples, however could you confirm if my microfluidic CRC circuit is considered to be complex impedance?
  2. The warning states "Do Not Calibrate the System with a Complex Impedance" and given the fact that correct measurements require accurate calibration, could you shed some light on the accuracy range I will expect on the CRC circuit and confirm if the AD5933 is a suitable tool to measure the impedance of the conduction cell?

 

Thank you for your time.

 

Raymond

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