Impedance analyzer
An impedance analyzer is an electronic measuring instrument used to measure complex electrical impedances as a function of frequency . Impedance is an essential parameter for characterizing electronic components , electronic circuits and the materials used to manufacture components. Impedance analysis is also generally used to characterize materials with dielectric behavior, such as biological tissues, food or geological samples.
Impedance analyzers are available in three significantly different device versions. With these three versions, measurements from the ultra- low frequency to the ultra-high frequency range can be carried out and impedances from micro to tera ohms can be determined.
functionality
Impedance analyzers measure the complex electrical impedance as a function of frequency. For this, the phase-dependent measurement of current and voltage is carried out on a test object while the measurement frequency is varied. The most important specifications of an impedance analyzer are the frequency range, the impedance range, the absolute impedance accuracy and the phase angle accuracy . Other specifications include the ability to apply voltage and current biasing during measurement and the measurement speed.
Impedance analyzers typically allow highly accurate impedance measurements, e.g. B. a base accuracy of up to 0.05%, and a frequency range of micro to Giga hertz . The impedance range extends over many decades from micro- to teraohm, while the phase angle accuracy is in the range of 10 milligrades. Measured impedance values include the absolute impedance, the real and imaginary parts of the measured impedance, and the phase between voltage and current. Impedance parameters derived from the model, such as conductance , inductance and capacitance , are calculated and displayed on the basis of an equivalent switching model.
In contrast to impedance analyzers , LCR measuring devices offer functions for impedance measurement, typically with similar accuracy, but in the lower frequency range, but above all with a fixed measuring frequency. Correspondingly, only one data pair or a maximum of a few support points and not an entire impedance spectrum is measured.
| Procedure | Frequency range | Impedance range | Basic accuracy |
|---|---|---|---|
| direct IV (direct current-voltage measurement) | µHz to 50 MHz | 10 µΩ to 100 TΩ | 0.05%. |
| ABB (Auto-balanced Bridge) | 20 Hz to 120 MHz | 10 mΩ to 100 MΩ | 0.05% |
| RF-IV (Radio Frequency Current-Voltage) | 1 MHz to 3 GHz | 100 mΩ to 100 kΩ | 1 % |
A fourth implementation, the network analyzer (VNA), can be viewed as a stand-alone instrument. Unlike impedance analyzers, VNAs also measure impedance, but at much higher frequencies and with less accuracy than impedance analyzers.
Applications
Impedance analyzers have a wide range of applications, such as material analysis, component characterization, component testing and bioimpedance.
Reactance table
Most impedance analyzers are equipped with a reactance table which shows the reactance values for the capacitive reactance XC and the inductive reactance XL for a certain frequency. The accuracy of the instrument is transposed on the diagram, this way the user can quickly see which accuracies can be achieved at a certain frequency and reactance.
Individual evidence
- ^ Zurich Instruments: What makes a great Impedance Analyzer? Retrieved August 9, 2019 .
- ↑ a b c Impedance Measurement Handbook. (PDF) Keysight Technologies, November 2, 2016, p. PDF , accessed on August 9, 2019 .
- ↑ Vytautas Dumbrava, Linas Svilainis: Uncertainty analysis of IV impedance measurement technique. Accessed August 9, 2019 .
- ↑ M. Horibe: Performance comparisons between impedance analyzers and vector network analyzers for impedance measurement below 100 MHz frequency . In: 2017 89th ARFTG Microwave Measurement Conference (ARFTG) . 2017, p. 1–4 , doi : 10.1109 / ARFTG.2017.8000837 .
- ↑ Harold A. Wheeler: Reactance Chart. (PDF) Retrieved on August 9, 2019 .