Hello,

I have problem understanding how the phase is calculated in the user guide of the AD5933 evaluation board.

Phase is atan(Imaginary/real).

In figure 16 of the user guide (http://www.analog.com/media/en/technical-documentation/user-guides/UG-364.pdf), for 30000Hz, imaginary is 8990 and real is -3726. How is the phase -7.88e-2 (close to 0)?

Thank you.

Hi,

The real and imaginary values shown in figure 16 of the user guide is for the frequency sweep of the unknown impedance. As for the phase in figure 16 of the user guide, it is calculated from the difference of the phase of the system with the unknown impedance minus the phase of the system with the calibration impedance. That is, two calculations for phase is being done in obtaining the phase due to the unknown impedance.

Best regards,

Mark