RF impedance measurements by voltage-current detection

Abstract

A RF impedance measurement technique using the V-I probe is discussed in comparison with the vector reflectometer. The V-I probe samples voltage and current of a DUT (device under test), the impedance of the DUT being determined from the complex ratio of the sampled values. A calibration procedure with standard devices is used to eliminate the nonideal characteristics of the probe. Theoretical and experimental analyses suggest that better accuracy can be realized by the V-I method than by the vector reflectometer in lower and higher impedance measurements for the frequency range extending beyond 500 MHz. The combination of the V-I method and reflectometry is suggested as a means to provide accurate measurements in a wider impedance range. >