Ground Isolated Acquisition Circuit for Control Moment Gyroscope Noise Reduction
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Solution Overview
Problem
Data acquisition circuits in space applications face poor signal-to-noise ratio due to leakage current and difficulty in achieving high common mode rejection and gain, especially in broadband sensors, which limits their precision and accuracy.
Innovation Solution
A fully differential ground isolated acquisition circuit with a ground reference correction circuit and ultra-high impedance output circuit is used to improve the signal-to-noise ratio by isolating noise from the quiet ground and applying correction signals, allowing for increased gain without introducing detectible noise across full bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional data acquisition circuits are used in space applications, then the circuit can process broadband sensor signals, but the signal-to-noise ratio is poor due to leakage current and difficulty in achieving high common mode rejection
Solution Approach 1:
The patent introduces an intermediary ground reference correction circuit that mediates between the differential signal path and ground. This circuit includes a ground reference sensor that detects ground potential and generates correction signals to compensate for common mode noise and leakage current effects, thereby improving signal-to-noise ratio without sacrificing broadband capability
Solution Approach 2:
The patent applies equipotentiality by maintaining a stable ground reference potential through the ground reference correction circuit. By keeping the ground reference at a constant potential and correcting deviations, the circuit achieves high common mode rejection while maintaining broadband signal acquisition capability
2Measurement precision
If high gain is increased to improve signal-to-noise ratio through signal chain, then the signal-to-noise ratio improves, but detectible noise is introduced across full bandwidth
Solution Approach 1:
The patent extracts the ground reference correction function into a separate, dedicated circuit block that operates independently from the main signal amplification path. This separation allows high gain to be applied to the differential signal while the correction circuit handles noise reduction separately, preventing detectible noise introduction
Solution Approach 2:
The ground reference correction circuit performs preliminary noise reduction and signal conditioning before the main amplification stages. By correcting common mode errors and leakage current effects early in the signal chain, the subsequent high-gain stages can amplify the corrected signal without amplifying the original noise, thus improving signal-to-noise ratio without introducing detectible noise
Data Source
AI summary
An acquisition circuit for a vehicle or other system is provided. The system, for example, may include, but is not limited to a control moment gyroscope, and a fully differential ground isolated acquisition circuit communicatively connected to the control moment gyroscope and configured to acquire a differential data signal on the control moment gyroscope and output the differential data signal to at least one output node. The acquisition circuit may include, but is not limited to a ground reference correction circuit configured to recenter the differential data signal on at least one output node, and at least one ultra-high impedance output circuit coupled between the ground reference correction circuit and the input differential circuit.