RE AD5933 Capacitance Measurement

Q 

As we know that AD5933 can measure both the magnitude and phase of impedance.
So, I would like to know if we use this information to estimate the resistance
value and capacitance value when a RC network is being measured. Did you have
any experience or suggestion on this question.

 

A 

It seems that we are unable to extract the R and C values separately using only
one excitation frequency from AD5933.
On the other hand, I have added the functions in GUI to display the real and
imaginary contents presented by AD5933. But, I could not find any obvious link
between changes of the two parts and the acupuncture point measured. 

Comments
Anonymous

  • Most certainly both R and C values can be calculated from a single-frequency measurement.

    If (through proper AD5933 calibration) the magnitude M and phase Ph are measured at a given frequency w, the resistance R and capacitance C can be calculated as follows:

    1. For sequential RC network: R = M*Cos{Ph), C = 1 / (w*M*Sin(Ph))

    2. For parallel RC network: R = M / Cos(Ph), C = Sin(Ph) / (w*M)

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