Impedance calibration (L, C, R)

Impedance measuring instruments use different measurement principles to measure impedance as a vector quantity either in general way (in modern instruments by measuring vector ratio of voltage and current over the unknown impedance), or as a specific quantity (i.e. capacitance, inductance, or AC resistance). In any case at least two parameters need to be measured, one corresponding to reactive component of impedance vector, and the other corresponding either to resistive component or to the ratio of both components (dissipation and quality factor). Impedance measuring instruments can measure, depending upon design, many parameters, at different measuring signals and frequencies, and in several ranges.

In all impedance measurements two parameters need to be measured at least to determine the impedance as a complex quantity. Most modern impedance measuring instruments (meters based on current to voltage conversion, automatic bridge method, vector impedance meters, reflectometer bridge meters, etc.) measure real and imaginary parts of an impedance vector and then convert them into the desired parameters such as |Z|, θ, |Y|, R, X, G, B, C, L, D, Q.

The older types of instruments, mainly based on bridge methods, are usually optimized to measure either capacitance (transformer ratio type bridge, Schering bridge, etc.) or inductance (Maxwell-Wien bridge, etc.). There are also special types of measuring instrument, i.e., based on resonance method, used for Q measurements, low inductance measurements, or high frequency inductance measurements.

Knowledge of the measurement principles employed in different kinds of measuring instruments is necessary in determining the appropriate measurement method to assure quality of your application. SIQ can support you by providing accredited certification and share impedance measurement experiences.