The UHFLI from Zurich Instruments is a digital lock-in amplifier that covers the frequency ranging between DC and 600 MHz. In addition to the highest operation frequency among all commercial lock-in amplifiers, the UHFLI also provides the lowest time constant of 30 ns for demodulation, which results in a demodulation bandwidth greater than 5 MHz.
The analog front end provides an excellent noise performance of 4 nV/√Hz, which helps in several applications to keep the signal-to-noise ratios high, while accelerating the measurement. In combination with the most advanced instrument control software LabOne®, the UHFLI is the flagship all Zurich Instruments products and also signifies the sophistication of today’s scientific instrumentation.
The main features of the UHFLI amplifier are as follows:
- Two high-performance signal generators
- FFT spectrum analyzer with 5 MHz span
- Four independent harmonics per lock-in unit
- Two independent lock-in units
- High-resolution 12-bit scope with 65k samples
- LabOne toolset (Linux and Windows)
- Operates at a frequency of 600 MHz
- Frequency response analyzer (FRA)
The main applications of the UHFLI amplifier are as follows:
- Nano and quantum physics: Single electron transistors, noise measurement, MRFM, graphene, quantum computing
- Sensors and actuators: NEMS, MEMS, for example accelerometers, gyroscopes, etc.
- Scanning probe microscopy: Scanning near-field optical microscopy (SNOM), high-speed AFM
- Medtech: Electrical impedance spectroscopy, flow cytometry
- Industrial production: RFID transmission demodulator, non-destructive testing (NDT), chip testing, and failure analysis
- Confocal microscopy, laser spectroscopy: ultra-high speed scanning, THz spectroscopy
- Engineering research and development: FFT spectrum analyzer, vector network analyzer (VNA), oscillator testing, and FRA
UHFLI Functional Diagram
The two signal inputs and two signal outputs effectively provide two lock-in amplifiers in a single instrument. Each lock-in amplifier unit consists of four double-phase demodulators that simultaneously provide X, Y, R and Θ.
High-Precision Signal Inputs
The UHFLI’s two signal inputs provide superior noise specifications and work in single-ended mode. Input coupling can be selected from high impedance to 50 Ω which suits both high-speed and low-frequency applications. The UHFLI is provided with two extra input and two extra bidirectional connectors intended for precise triggering and external reference mode on external events. It also supports dual-auto and dual-internal reference modes.
The UHFLI produces two low-distortion sinusoid outputs suitable for driving the most modulating devices or the device under test. The UHF-MF multi-frequency option offers six supplementary oscillators and enables the production of a liner combination of up to eight sinusoids. Extra connectors on the front panel offer the phase, demodulated amplitude, or quadrature signals, square wave references, or trigger signals for external hardware.
Demodulators and Filters
The UHFLI is provided with eight dual-phase demodulators designed for concurrent measurement at four harmonic frequencies per signal unit. Each demodulator possesses separately configurable filter parameters. The measured phase and amplitude data after demodulation, are streamed in real-time to the host computer.
A trigger and reference network offers superior performance operation: reference input and output work at a bandwidth of 600 MHz, trigger input and output has reaction times down to 100 ns. The UHFLI is the primary lock-in amplifier with special software and hardware trigger functionalities.
Hardware triggers enable fast reaction to physical conditions, while software triggers offer an infrastructure to characterize complex trigger criteria. Triggers are utilized to output demodulated samples at particular points in time, or to coordinate actions between various functional domains inside the UHFLI.
The arithmetic unit facilitates quick computation on a multitude of measurement data. This processor has multiplication, division, addition, and subtraction of all data that are present on the auxiliary outputs. Applications include normalization by a reference, balanced detection, or dual-frequency resonance tracking.