I am using AD5933 to find the impedance of an unknown sample.
For this first I attenuated the the AD5933 output to around 30 m Vpp ( as it is required for our sample) and applied to sample. Currently I am using potentiometer as a sample impedance. On the receive side I collected the real and imaginary parts using Arduino Nano board. After that I measured the impedance using the gain factor which I had obtained from the calibration of the AD5933.
Problem is that as I linearly change the sample impedance (potentiometer) I am not able to get the linear change at the measured impedance, instead at some impedance points value peaks. Then to understand the problem I repeated the same kind of measurements using AD5933 evaluation board and found that the results are perfectly fine.
So, can any one please guide why AD5933 is behaving like that, i.e impedance measured is not linearly changing as I keep changing the sample impedance (potentiometer)
Please find the attached plot showing the comparison of evaluation board results and the AD5933 results that obtained by measuring
The figure uploaded was not annotated properly
[edited by: Shambhu_nd at 11:42 AM (GMT -4) on 4 Jul 2021]