Impedance calibration (L, C, R)

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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.

Calibration of test equipment at SIQ

LCR meter

High precision LCR meters usually have 4 TP (terminal pair) BNC connectors which minimizes unwanted parasitic capacitances and better defines reference measurement impedance plane, which improves accuracy e.g. 0.05%. Comprehensive calibration of LCR meters includes the following calibration points:

  • test frequency
  • test voltage
  • DC bias
  • capacitance and dissipation factor
  • resistance
  • inductance

LCR meter (handheld)

Handheld LCR meters usually contain 2 terminal connections, which improves user experience in the sense of easy operation. On the other hand, it limits frequency range and accuracy. Typical calibration points are:

  • inductance
  • capacitance
  • resistance

Digital capacitance bridge

Digital capacitance bridge is the most accurate commercial instrument for capacitance and dissipation factor measurement on the market with high stability, resolution, linearity, and accuracy in the range of 5 ppm. It is used for capacitance working standard calibration. Calibration of digital capacitance bridge can also be covered by SIQ.

Impedance analyzer

Impedance analyzers are used for impedance frequency response measurement up to 100 MHz range and more. Their operation is constructed as a sweeper, which is perfect for impedance elements quality control. Calibration is performed in the sense of LCR meter.

Capacitance standards

Capacitance standards are 4 TP devices used for LCR meters calibration/verification. SIQ can perform calibration of capacitance and dissipation factor standards up to 10 MHz from 1 pF to 1 µF.

Inductance standards

Inductance standards are used for LCR meters calibration. SIQ can perform accredited calibration from 100 µH to 10 H from 100 Hz to 1 kHz.

Resistance standards

Resistance standards are 4 TP devices used for LCR meters calibration and can be calibrated from DC up to 10 MHz.

Capacitors, resistors, inductors (impedance elements)

SIQ also performs calibration of 2 TP/T (terminal pair/terminal) inductors, capacitors, and resistors up to 10 MHz.

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  • SIQ Ljubljana