Discovering the MF-IA Impedance Analyzer Option

This blog post introduces the MF-IA Impedance Analyzer option, which can be added to the MFLI Lock-in Amplifier to enhance it with the same impedance analyzer and precision LCR meter functionality as the MFIA Impedance Analyzer.

Adding the MF-IA option to your MFLI gives you the ability to measure the impedance of a device, material or component accurately and precisely. The impedance measurement frequency range is the same as that of your instrument, namely from 1 mHz to 500 kHz or 5 MHz. Practically, the MF-IA option provides an Impedance Analyzer module as shown in Figure 1. Impedance measurements can be taken in the Sweeper, Plotter and DAQ modules of LabOne^® along with full API control.

But what are exactly the requirements for impedance measurements?

Impedance measurements require the precise measurement of voltage, current and phase. This needs to take place over a frequency range of interest during which the impedance will be changing. It is also necessary that the impedance of other components in the measurement loop can be neglected by a compensation routine, or that a low-parasitic fixture is used to ensure that the measured impedance relates purely to the sample under test. Finally, it is necessary to calculate the impedance by applying a model to the fundamental signals captured in the measurements.

The MFLI gains precisely this type of additional capability for impedance measurements thanks to the MF-IA option. Let's look at the functionality offered by the MF-IA option in more detail:

• Additional demodulator to allow for simultaneous measurements of current and voltage, enabling both 2- and 4-terminal impedance measurements.
• Autoranging of current and voltage input when using the Sweeper tool to enable swept measurements even when the impedance changes with frequency.
• Real-time calculation of impedance parameters based on the following two-component models: Rp||Cp, Rs+Cs, Rs+Ls, G-B, D-Cs, Q-Cs, D-Ls, Q-Ls.
• Included MFITF Impedance Test Fixture. The MFITF has very low parasitic impedance (> 2 fF) and a PCB-based sample carrier system that allows you to change samples fast and to use your own custom design of carriers.
• Internal factory calibration that guarantees accurate measurements using the MFITF and sample carriers without the need for any additional compensation routine.
• User Compensation advisor to account for the parasitics of external cables, fixtures and other components in the measurement loop. Flexible compensation routines can be run over a user-defined frequency range and in any combination of short, load and open stages. The resulting compensation file can be saved and reloaded. Such compensation step is critical for accurate and repeatable impedance measurements.
• Current zone ranging feature, thanks to which the Sweeper can apply user-defined input ranges for a given frequency. This is especially useful for low frequency sweeps and for applications where the lower current input ranges must be used in combination with the Sweeper tool. Choosing the lowest current input ranges of 1 nA and 10 nA gives access to impedance measurements up to 1 TΩ.
• One-period averaging feature for low-frequency measurements, which is relevant for data acquisitions below 10 Hz and down to 1 mHz. This saves time when measuring sweeps by measuring in one period per data point; it is especially useful for electrochemical impedance spectroscopy.

In summary, installing the MF-IA option allows you to take accurate impedance measurements while maintaining the full functionality of your MFLI. You will be able to measure impedances from 1 mΩ to 1 TΩ and from 1 mHz to 500 kHz or 5 MHz. Thanks to the specifications of the MFLI Lock-in Amplifier, it is also possible to measure impedance at a fixed frequency very fast: for example, in 10 us for a test signal of 1 MHz. Such fast measurements suit applications such as sensor characterization and impedance transient spectroscopy. Overall, the MF-IA option gives you a powerful impedance analyzer and precision LCR meter surpassing the accuracy and functionality of most impedance analyzers on the market today. Technical support from our team of impedance measurement specialists will ensure that you get up and running as smoothly and quickly as possible.

If you would like to test impedance measurements on your MFLI, please get in touch with us so that we can set up a one-week trial of the MF-IA option.