Capacitive Acceleration Sensor Temperature Compensation
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Solution Overview
Problem
Miniaturized acceleration sensors face challenges in accurately measuring acceleration due to temperature-induced non-uniform stress and displacement of electrodes, leading to detection errors and common mode noise.
Innovation Solution
A capacitive acceleration sensor system with an acceleration detection part and an offset detection part, utilizing differential charge-to-voltage or charge-to-voltage converters to process outputs and reduce temperature dependence, and incorporating a trimming process to cancel base capacitance and variable capacitor differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If miniaturized acceleration sensors are used, then device size is reduced, but measurement precision deteriorates due to temperature-induced non-uniform stress and electrode displacement
Solution Approach 1:
The sensor is divided into multiple independent electrode pairs (first electrode pair and second electrode pair) that can be processed separately. Each pair generates its own output signal, allowing independent compensation for temperature effects in each channel while maintaining the miniaturized structure.
Solution Approach 2:
A differential amplifier is introduced as an intermediary component between the electrode pairs and the output. This amplifier processes the differential signals and common mode components, enabling temperature compensation through differential signaling while preserving the compact sensor design.
2Measurement precision
If temperature compensation is implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The system uses differential signaling where the output is the difference between two electrode pairs. This inherent feedback mechanism automatically compensates for temperature effects since both pairs experience similar thermal stress, and the differential amplifier rejects common mode temperature-induced signals.
Solution Approach 2:
The patent changes the signal processing approach by converting absolute capacitance measurements into differential voltage measurements. This parameter transformation enables temperature compensation through differential signaling while using standard amplifier circuits rather than complex compensation networks.
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
The system effectively reduces detection errors caused by temperature changes and common mode noise, maintaining low temperature dependence and improving detection accuracy.
Implementation Method 1
a capacitive acceleration sensor using a MEMS technique is known in the related art
Implementation Method 2
utilizing differential charge-to-voltage or charge-to-voltage converters to process outputs and reduce temperature dependence
Data Source
AI summary
An acceleration sensor system, includes: an acceleration sensor including an acceleration detection part and an offset detection part; and a processing part configured to process respective outputs of the acceleration detection part and the offset detection part, wherein the acceleration detection part includes a first electrode, a second electrode, and a third electrode provided between the first electrode and the second electrode, wherein one of each of the first and second electrodes and the third electrode is a fixed electrode while the other of each of the first and second electrodes and the third electrode is a movable electrode, wherein the offset detection part includes a fourth electrode, a fifth electrode, and a sixth electrode provided between the fourth electrode and the fifth electrode, and wherein the fourth electrode, the fifth electrode, and the sixth electrode are fixed electrodes.