The code presented here concerns the impedance frequency response measurement of a two-terminal circuit using the DAQ-system NI USB-6211. The measurement is based on the Discrete Fourier Transform (DFT) and Maximum Likelihood estimation (MLE) of the amplitude and phase of the voltage across- and the current through- the two-terminal circuit. Then the impedance modulus and phase is calculated. The excitation of the device under test is performed via single-tone sine wave signal with stepwise increasing frequency. The measurement setup is given in the .zip file. The code provides:
1) a plot of the impedance frequency response (modulus and phase) of the two-terminal circuit;
2) ImpedanceRespData.mat file with the measurement results (for post-processing).
The code is based on the theory described in:
 H. Zhivomirov, I. Iliev. Impedance Frequency Response Measurement with Matlab Implementation. Journal of the Technical University of Gabrovo, ISSN: 1310-6686, Vol. 52, pp. 61-65, 2016. (umis.tugab.bg/prep/tomove/10/52-03-EE-01-min.pdf)
 NI USB-621x Specifications.pdf. Austin, National Instruments, Corp., 2009.
H. Zhivomirov, I. Iliev. Impedance Frequency Response Measurement with Matlab Implementation. Journal of the Technical University of Gabrovo, ISSN: 1310-6686, Vol. 52, pp. 61-65, 2016. (umis.tugab.bg/prep/tomove/10/52-03-EE-01-min.pdf)
Hristo Zhivomirov (2021). Impedance Frequency Response Measurement with Matlab (https://www.mathworks.com/matlabcentral/fileexchange/50637-impedance-frequency-response-measurement-with-matlab), MATLAB Central File Exchange. Retrieved .
Hi Nauman! Thanks for the interest! I use a resistor with value of 0.1 Ohms like simple current-to-voltage convertor (i.e., shunt).
Both input and output are voltage signals. What kind of circuit are you using to convert one of them in to current signal?
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