Introduction

Realization (using analog, digital and mixed signals technologies) of low noise amplifiers with high dynamic range (higher than 100 dB) with output signal to noise ratio higher than the input. These amplifiers use variable gain amplifiers with automatic gain control loops and coherent modulation/demodulation techniques.

Technical features

The necessity of weak signals buried in disturbances and noises has pushed ENEA to develop and patent electronic devices that extend the capabilities of the standard lock-in amplifiers. The main limitation of the coherent modulation/demodulation technique (lock-in amplifier) is the limited dynamic range. High dynamic range input signals may saturate the input stages of the lock-in amplifier, fail the signal recovery and produce erroneous measurements. All the commercial lock-in amplifiers use adjustable but fixed scales, therefore the user is obliged to set a scale that avoid saturation but it may not match the actual dynamic range of the input signal. Using a low-noise, variable gain front-end-amplifier and a closed feedback loop is possible to match the input dynamic range with signal’s propriety, optimizing the measurement accuracy and avoid incorrect measurements without manual intervention.

Possible Applications

• Biomedical applications: ecografy, body scanner, etc;
• Secure electrical communications;
• RADAR, SONAR, ECM, ESM;
• Instruments for nuclear physics experiments;
• Tri-dimensional, high resolution laser scanners;
• Quantum computing.

Advantages

• Higher dynamic range respect the usual lock-in amplifiers;
• Real-time, automatic optimization of the input dynamic range with varying input signals;
• Improvement usable on existing analog and digital lock-in amplifiers;
• Better measurements accuracy.