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Related Experiment Video

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The Frequency Domain Thermoreflectance Technique for Thermal Property Measurements

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Published on: December 5, 2025

Frequency-following reference oscillator for a two-phase lock-in amplifier.

¹Bell Laboratories, Murray Hill, New Jersey 07974.

The Review of Scientific Instruments

|May 1, 1979

Summary

A new frequency-following oscillator circuit provides a stable reference for lock-in amplifiers. It effectively tracks drifting, intermittent, or low-amplitude signals, improving measurement accuracy in applications like Brownian motion studies.

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Area of Science:

Electronics
Physics
Instrumentation

Background:

Lock-in amplifiers require stable frequency references for accurate signal detection.
Tracking weak or drifting signals, such as those in Brownian motion, presents significant challenges for traditional instrumentation.

Purpose of the Study:

To describe a novel frequency-following oscillator circuit.
To enable a stable, commensurate reference signal for two-phase lock-in amplifiers.
To enhance the tracking of challenging signal types.

Main Methods:

Implementation of a frequency-following oscillator circuit.
Integration of digital hysteresis for adaptive tracking correction.
Application in conjunction with a two-phase lock-in amplifier.

Main Results:

The circuit successfully generates a commensurate reference signal.
Effective tracking of signals with slow frequency drift was demonstrated.
The device showed utility in handling intermittent or low-amplitude signals.
Digital hysteresis optimized tracking corrections based on signal-reference proximity.

Conclusions:

The developed frequency-following oscillator is a valuable tool for lock-in amplifier applications.
It provides robust performance for signals with challenging characteristics.
The use of digital hysteresis enhances tracking stability and accuracy.