LCR Meter vs Impedance Analyzer

We are often asked about the difference between LCR Meters and Impedance Analyzers, especially since the MFIA offers the functionality of both instruments.

LCR-meters and impedance analyzers are fundamentally similar, in that they both measure impedance parameters such as capacitance, inductance and resistance.They achieve this by measuring the phase-sensitive voltage-to-current ratio. This ratio gives the fundamental impedance values such as absolute impedance and phase, along with the real and imaginary part of the impedance.

From these fundamental measurements, impedance parameters can be derived by applying a user-defined equivalent-circuit model to the fundamental values. These parameters include capacitance, inductance and resistance (hence the name LCR-meter). In addition, further parameters including q-factor, dissipation and conductance can also be derived.

An impedance analyzer includes this functionality, but also offers the capability to sweep the frequency and graphically display the acquired impedance parameters. This is in contrast to LCR meters which acquire at a fixed frequency. That said, some LCR meters may acquire at many different fixed frequencies, so impedance parameters can be interpolated from the data in an additional step.

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Figure 1: LabOne screenshot showing the MFIA numeric tab. The device under test is a 10 mH SMD. The test signal is 0.5 V and the test frequency is 100 kHz..

To access the LCR-meter functionality of the MFIA, select the numeric tab as shown in Figure 1. Here, it’s possible to view the fixed measurement frequency, and acquired impedance parameters. The numeric tabs can be freely configured to show the parameters relevant to your experiment, and any fixed-frequency can be selected between 1 mHz and 5 MHz. With the optional MF-MD option, you can even measure simultaneously at two different frequencies

The values displayed in the numeric tab can also be plotted in the time domain using the plotter tab as shown in Figure 2. The plotter displays multiple parameters as a function of time, and allows you to export the display in vector graphics, or the data in csv format for further analysis.

 

Figure 2: LabOne screenshot showing the plotter tab. The plotter displays the selected impedance parameters as a function of time, in this case, abs(Z), phase and inductance. The horizontal scale is time (in seconds) after starting the measurement.

To use the MFIA as an impedance analyzer open the sweeper tab shown in Figure 3. The sweeper allows you to sweep the measurement frequency (or other parameters such as offset bias) and acquire impedance parameters as a function of frequency. The auto-range function of the sweeper means you can sweep continuously from 1 mHz to 5 MHz and all the range changes are handled automatically.

 

Figure 3: LabOne screenshot showing the Sweeper tab of the MFIA. A continuous sweep of abs(Z), phase and inductance of a 10 mH inductor from 1 Hz to 5 MHz is shown.

 

The MFIA is both a precision LCR meter and an impedance analyzer, and the user can seamlessly switch between these capabilities. Furthermore, the user can use both capabilities simultaneously on the MFIA thanks to the powerful LabOne software which allows multiple tabs to operate simultaneously. This means you don’t have to choose between an LCR-meter and an impedance analyser, you can now have both in one instrument.