The Zurich Instruments VHFLI is a high-performance digital lock-in amplifier designed for demanding signal analysis, measurement and control applications from DC to 50 MHz, with the optional VHF-F200M upgrade extending the operating range to 200 MHz. Combining low-noise analogue inputs with high-speed digital signal processing, the VHFLI provides precise measurements of weak signals across a wide dynamic range.
The VHFLI incorporates two independent lock-in units, each providing a voltage and current input, allowing simultaneous measurement of multiple signals. Voltage input ranges extend from ±5 mV to ±2 V, while current inputs cover ±10 nA to ±10 mA. Input voltage noise is below 3 nV/√Hz above 50 kHz, supporting sensitive measurements where low noise is critical.
Up to eight dual-phase demodulators and eight programmable numerical oscillators are available, allowing multiple frequency components and harmonics to be measured simultaneously. The instrument provides a minimum time constant of 30 ns, while individually configurable digital filters enable precise control of measurement bandwidth and signal processing. The VHF-MD multi-demodulator option adds flexible arbitrary-frequency measurements across all eight demodulators.
High-speed 14-bit, 2 GSa/s A/D and D/A converters support rapid signal acquisition and generation. Two analogue signal outputs operate up to 200 MHz with the appropriate configuration, while USB-C, 1 GbE Ethernet and 32-bit digital I/O provide flexible integration with laboratory automation and measurement systems.
The VHFLI is controlled through LabOne®, Zurich Instruments’ integrated software environment, which provides tools including an oscilloscope, spectrum analyser and sweeper. Optional modules add arbitrary waveform generation, PID/PLL control, modulation analysis and boxcar averaging, allowing the instrument to be configured around specific experimental requirements.
Applications include Raman and pump-probe spectroscopy, THz spectroscopy, nano-optomechanics, quantum sensing, MEMS/NEMS characterisation, scanning probe microscopy and laser voltage probing.
