Impedance meter based on cross-correlation noise measurements

In this paper we demonstrate how it is possible to exploit cross-correlation techniques in order to estimate a DUT impedance or admittance by means of noise measurements. The potential advantages of such an approach over conventional RLC meters are the absence of any external excitation source and that the entire impedance vs frequency plot can be obtained in almost real time with the measurement accuracy improving with measurement time. A prototype of such a cross-correlation based impedance meter has been realized and tested. The results of the performed experiments demonstrate the effectiveness of the proposed approach.