MFLI Lock-In Amplifier – for Medium and Low Range Frequency Measurements

The MFLI amplifier from Zurich Instruments is a digital lock-in amplifier that sets the new benchmark for measurements in the low and medium frequency range. The MFLI is available in two versions that cover the frequency range DC to 500 kHz to DC to 5 MHz. It is possible to upgrade the amplifier from 500 kHz to 5 MHz later.

The MFLI integrates high performance with the exceptional LabOne® toolset with the help of carefully devised analog and digital front ends in combination with the advantages of rapid digital processing, which is provided by the on board FPGA. The embedded web and data servers enable simple connection to any device running a web browser.

Key Features

The main features of the MFLI amplifier are as follows:

  • Plug and play with embedded LabOne® web server
  • DC - 500 kHz/5 MHz, 60 MSa/s, 16 bit
  • Battery operation uses AC line and DC supply
  • LabOne toolset includes sweeper, scope, spectrum analyzer, etc.
  • Current and differential voltage inputs
  • USB 2.0 and 1 GbE high-speed connections
  • Upgradeable in the field with options


The main applications of the MFLI amplifier are as follows:

  • Materials research
  • Nano- and quantum-electronics
  • Scanning tunneling microscopy
  • Four-terminal sensing
  • Seismic measurements
  • Optical chopper applications
  • Pulsed laser applications, such as high power lasers
  • Low temperature physics

MFLI Functional Diagram

Front Panel Interface

The front panel of the MFLI has one differential voltage input, one current signal input, two auxiliary inputs, and one differential signal output that can function as reference inputs, and four auxiliary outputs.

The signal inputs and outputs can be operated in differential and single-ended mode for experiments that require additional immunity from noise disturbances. The signal ground can be attributed either to the BNC shield of the signal inputs or to the instrument ground.

Voltage and Current Measurements

Both current and voltage measurements are supported by the base instrument, but the simultaneous measurement of voltage and current requires the MF-MD multi-demodulator option. The analog front-end has AC/DC coupling selection as well as variable input impedance and the high-frequency analog to digital sampling provides a large over sampling factor, guarenteeing superior lock-in performance and high signal fidelity for the Scope.

Output Channels

The lock-in measurement results of the X, Y, R and Θ for each of the demodulators can be used in the following ways:

  • Transferred to the host PC over one GbE or USB 2.0 and displayed on the LabOne® user interface, where it can be analyzed with one of several LabOne tools, or simply stored locally using a few mouse clicks.
  • Analog output to any one of the four auxiliary outputs on the front panel. Individual offsets and scaling can be set for all of the signals and the 612 kSa/s sampling rate guarantees that all demodulated signal elements are reliably present on the physical connectors. The signal bandwidth is identical for all signals and can be as high as 200 kHz.
  • Results are stored locally in a USB mass storage device that is plugged in into one of the two USB connectors.

Back Panel Interface

The back panel provides additional BNC connectors consisting of two trigger inputs, two trigger outputs, and one input and one output for 10 MHz clock synchronization. Also, a SCSI connector provides access to each and every DIO channel. The units can be operated with the help of standard 90 - 240 V mains supply or with an external 12 V DC power supply, for example, from an external battery pack to break up ground loops.

Zurich Instruments/

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