Hi Dmitry Dmitriev ,

if your question is still relevant:

In order to measure the current, you need a resistor of low resistance and as little inductance as possible, or better, a current clamp with output for an oscilloscope, with the necessary bandwidth, of course. With the oscilloscope, you can compare voltage and current. Then:

|Z| = amplitude of voltage / amplitude of current (Ohm's law)

|phi| = 2 * pi * t / T

with t = time shift of current compared to voltage, T = 1 / frequency

If the current is earlier than the voltage, then phi (of the current) is positive, otherwise negative.

phi of the impedance = -phi of the current

Re(Z) = |Z| * cos(phi), Im(Z) = |Z| * sin(phi)

If you would like to carry out the measurements and the calculations automatically, you would need a signal generator and an oscilloscope with digital interface like IEC-625.

Joerg Fricke , thank you for your response. I will take into consideration the method you described.

if this discussion is still open and relevant...

can try the TDR method as shown on page 2 of https://abhargava.files.wordpress.com/2014/01/performing-tdr-analysis-using-agilent-ads.pdf.

connecting sig gen output (generating a pulse signal) to a series resistor 50 ohm, and followed by the DUT.

then measure the voltage before and after the 50 ohm resistor, use the eqn. on page 2 of this document to compute the impedance.

Dmitry,

I assemble and use for a while an impedance setup based on WFG and scope, using so-called a reference resistor channel. The idea is following: you apply the same wave (sin wave at given frequency) from WFG to your sample and reference and than you record the wave, which pass the reference channel and your sample. Then for each frequency you obtain on the scope the pairs of change in Amplitude (mV) and phase (deg) between sample channel and reference channel. The resistivity in reference channel should be more or less the same as total impedance of the sample. (this is by the way the weak point of this measurement scheme, as if the impedance in sample channel will change fast, then you can not "balance" these channels). Nevertheless, you will obtain the pairs of amplitude and shift for each frequency. Swapping through frequencies you will get the freq. dependence of amp and phase. Later you can convert amp and phase to resistivity in Ohm-m, using the value of resistor in reference channel and geometry of sample. The advantage of this setup is possibility to reach sub mHz range, which is not accessible by impedance meters. The setup works pretty good in sub micro Hz to 500 kHz, for load kOhms-100s of kOhms

any questions?

VB