AC-Excited Bridge Sensor Circuit for White Noise Suppression
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Solution Overview
Problem
Traditional bridge sensors in consumer electronic products face challenges due to their lightness and thinness, resulting in small strain and resistance value changes, which are heavily impacted by noise, leading to low detection accuracy.
Innovation Solution
A detection circuit that includes an alternating current excitation module, a signal conditioning module with an instrumentation amplifier and anti-alias filter, and a processing module using demodulation techniques to suppress white noise and improve signal-to-noise ratio, specifically applying an alternating current excitation signal to the bridge sensor and employing quadrature demodulation and correlated double sampling to enhance detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a direct current voltage source or direct current source is applied to the bridge sensor, then the detection circuit can obtain pressure or temperature data, but the system suffers from high white noise and low signal-to-noise ratio
Solution Approach 1:
The patent applies periodic AC excitation signals to the bridge sensor instead of continuous DC excitation. The excitation signal alternates between positive and negative cycles, enabling the sensor to operate in a dynamic state that reduces the impact of white noise. The periodic nature of the excitation allows for synchronized detection and signal processing that enhances signal-to-noise ratio while maintaining measurement accuracy.
2Weight of moving object
If the bridge sensor is made lighter and thinner for consumer electronic products, then it can be integrated into devices like touch screens and wearables, but the strain and resistance value changes become extremely small, making the voltage signal very weak and highly susceptible to noise
Solution Approach 1:
By using periodic AC excitation, the patent enhances the dynamic response of the thin bridge sensor. The alternating excitation creates larger voltage swings during strain events compared to DC excitation, making the weak signals from thin sensors more detectable above the noise floor.
Solution Approach 2:
The patent replaces traditional DC electrical excitation with AC excitation combined with synchronous detection methods. This substitution allows for better signal extraction from the weak voltage outputs of thin sensors by using frequency-domain separation to distinguish signal from noise.
3Device complexity
If the bridge sensor structure is simplified for lightness, then it can be used in consumer electronics, but the detection circuit becomes more susceptible to noise interference
Solution Approach 1:
The periodic AC excitation method provides a way to maintain simple sensor structures while reducing noise susceptibility through signal processing. The regular timing of excitation cycles enables synchronized detection that filters out random noise, allowing simple thin sensors to achieve reliable measurements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces white noise, improves the signal-to-noise ratio, and increases detection sensitivity, enabling more accurate pressure and temperature measurements in harsh environments.
Implementation Method 1
an alternating current excitation module 11, and a signal conditioning module 12
Implementation Method 2
when a resistance strain gauge is used to form a bridge sensor for pressure detection, the bridge sensor may be installed on a specific surface of an elastic element. When the elastic element is strained, a resistance value of the resistance strain gauge may change slightly
Implementation Method 3
a signal conditioning module 12 and an analog-to-digital conversion module 13 which are connected in sequence
Implementation Method 4
a signal conditioning module 12 and an analog-to-digital conversion module 13 which are connected in sequence
Implementation Method 5
The processing module 14 is configured to demodulate the processed output signal to generate a demodulated output signal
Implementation Method 6
employing quadrature demodulation and correlated double sampling to enhance detection sensitivity
Data Source
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AI summary
Provided are a detection circuit of a bridge sensor, a chip and a detection system. The detection circuit includes (1): an alternating current excitation module (11), and further includes a signal conditioning module (12), an analog-to-digital conversion module (13) and a processing module (14) connected in sequence. The alternating current excitation module (11) is configured to apply an alternating current excitation signal to the bridge sensor (2). The signal conditioning module (12) and the analog-to-digital conversion module (13) are configured to sequentially process an output signal of the bridge sensor (2). The processing module (14) is configured to demodulate the processed output signal and obtain detection information of the bridge sensor (2) according to the demodulated output signal. In embodiments of the present disclosure, a white noise of the system can be greatly suppressed, and a signal-to-noise ratio of the system is improved, thereby improving detection performance of the bridge sensor.