Lock-in Amplifiers

Connecting the MFLI to an External Signal Generator

26.07.2019

This blog post describes how to use the MFLI Lock-in Amplifier with an external reference frequency. The reference frequency comes from a signal generator Model 6221 from Keithley which is used to apply higher voltage pulses or sinusoidal signals on the sample. In some situations the MFLI can be used...

Frequency-Domain Response of Lock-in Filters

19.03.2019

Introduction The response of a lock-in amplifier is characterized by the parameters of its low-pass filter (LPF), i.e., time constant and filter order. The temporal response of the LPF demonstrates the latency of measurement while its spectral response shows the noise characteristics of measured signals. This blog post explains how...

How to Demodulate Multi-frequency Signals such as AM, FM and PM

20.03.2018

Introduction When analyzing signals with multiple frequency components, it is important to measure the amplitude and phase of each frequency component accurately so that a change in the characteristics of one component does not affect the measurement of another frequency component. There are two different approaches to multi-frequency signal demodulation...

Measuring PLL/PID Bandwidths Under Real Experimental Conditions

14.11.2017

With the merging of the PLL and PID tab in LabOne for the MFLI and the UHFLI, the PID Advisor section is now identical for both types of feedback loops, and various system models can be tested. After all, a phase-locked-loop (PLL) is nothing more than a PID feedback on...

Outputting Low-Frequency Sinusoidal Signals on the AUX Output of the MFLI

30.05.2017

This blog post shows how to output sinusoidal signals on the AUX Output of the MFLI Lock-in Amplifier with the MF-MD Multi-Demodulator option. Keep in mind that AUX outputs are not designed to output sinusoidal signals as the Signal Output.

Noise Analysis of Signal Components

29.03.2017

In this blog post, we investigate the relation between the noise of signal amplitude and phase on one hand, and the noise of in-phase and quadrature components of the signal on the other hand. We try to respond to the wrong intuition stating that the standard deviation of signal amplitude is higher than the standard deviation of each signal components...

Fast Auto-Approach to Control Stepper Motor with the MFLI Threshold Unit

22.02.2017

In many applications where the distance between two objects needs to be reduced to a predefined gap, the ability to control a stepper motor with clear stop conditions from different sensors is of high practical interest. Such functionality can be used to bring an optical lens to the appropriate working...

RF Reflectometry Measurements of Quantum Dots

20.02.2017

Characterizing semiconductor spin qubits with radio-frequency (RF) reflectometry offers a speed advantage over low-frequency conductance measurements thanks to insensitivity to 1/f noise. In this blog post, the measurements of Josip Kukučka and his colleagues...

Compensating Delay-Induced Phase Shifts for High-Frequency Resonators

20.02.2017

Phase-locked loops (PLL) or other PID controllers on nano-mechanical resonators rely on clean phase signals that exhibit large slope, or significant phase shift, around the resonance frequency. For really high-frequency NEMS and opto-mechanical systems above a few tens or hundreds of MHz, any small delay can have significant effect on...

Time-Domain Response of Lock-in Filters

09.02.2017

The heart of a lock-in amplifier is a phase-sensitive detector that includes a signal mixer and a low-pass filter. In this blog post, we focus on the time response of the low-pass filters implemented in the Zurich Instruments lock-in amplifiers including the MFLI, the HF2LI and the UHFLI...