Research and Optimization of High-Performance Front-End Circuit Noise for Inertial Sensors

Area of Science:

• Astrophysics and Space Science
• Sensor Technology
• Electrical Engineering

Background:

• Inertial sensors are vital for China's Taiji program, aiming for space-based gravitational wave detection.
• Capacitive displacement sensing circuit performance at low frequencies (0.1 mHz to 1 Hz) is critical for mission sensitivity.

Purpose of the Study:

• To decrease low-frequency noise in capacitive displacement sensing circuits.
• To enhance capacitive sensing resolution for improved gravitational wave detection.
• To analyze and mitigate noise sources within the sensing circuit.

Main Methods:

• Analyzed pre-amplifier circuit noise characteristics.
• Precisely tuned the transformer bridge and evaluated transformer parameter effects on noise.
• Introduced a discrete JFET method to reduce operational amplifier current noise.
• Investigated the impact of feedback resistance and capacitance in TIA circuits on noise.

Main Results:

• Achieved a 23% improvement in capacitive sensing resolution, from 1.095 aF/rtHz to 0.84 aF/rtHz @ 10 mHz.
• Verified the proportional relationship between transformer noises and TIA noise before and after optimization.
• Successfully implemented an optimized TIA circuit and a superior transformer.

Conclusions:

• The study successfully reduced noise and improved capacitive sensing resolution.
• Findings offer valuable insights for further noise reduction and resolution enhancement in sensitive detection circuits.
• Optimized circuits and components are key to advancing space gravitational wave detection capabilities.