MEMS Sensor Detection Device Gravity Cancellation Circuit
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Solution Overview
Problem
Existing MEMS sensor systems face a trade-off between detection acceleration range and sensitivity, where high sensitivity limits the detectable acceleration range to ±1 g, failing to meet the requirements of high precision and sensitivity needed in applications like seismic exploration.
Innovation Solution
A MEMS sensor detection device incorporating a cancellation voltage generation circuit that generates a gravity cancellation voltage proportional to gravity acceleration, allowing for improved sensitivity through time-multiplexed and gravity cancellation technology, enabling the system to detect acceleration signals beyond ±1 g.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensitivity of the MEMS sensor system is improved by reducing the acceleration range to ±1 g, then the sensitivity increases to 4 V/g, but the detection acceleration range is limited and the system cannot normally operate at ±1 g locations
Solution Approach 1:
The patent implements periodic switching between feedback phase and gravity cancellation phase. During the feedback phase, the system maintains high sensitivity for small-range displacement detection. During the gravity cancellation phase, the system applies cancellation voltage to offset gravity effects, enabling detection of larger acceleration ranges. This periodic alternation allows the system to achieve both high sensitivity and extended detection range.
Solution Approach 2:
The patent changes the working state parameters of the MEMS sensor by switching between two distinct phases: feedback phase with high sensitivity configuration and gravity cancellation phase with extended range configuration. By dynamically adjusting the operational parameters through phase switching, the system overcomes the limitation of fixed sensitivity-range trade-off.
2Reliability
If the maximum output voltage of the readout circuit is fixed at 4V, then the system operates stably, but the sensitivity is limited to 2 V/g with an acceleration range of ±2 g
Solution Approach 1:
The system uses periodic phase switching to temporarily exceed the normal operating voltage constraints during the gravity cancellation phase. The cancellation voltage is applied only during its designated phase, allowing the system to achieve higher sensitivity (6 V/g) without causing continuous instability. The feedback phase restores normal operation to maintain overall system reliability.
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 solution effectively enhances the sensitivity of the MEMS sensor system, allowing it to detect acceleration signals up to ±0.5 g with a sensitivity of 6V/g, three times higher than prior art, while maintaining the maximum output voltage, thus addressing the limitations of existing systems.
Implementation Method 1
the MEMS sensor 10 is a capacitive MEMS acceleration sensor and is used for converting acceleration into weak signal output
Implementation Method 2
the feedback circuit 12 is used for generating a feedback voltage VF proportional to the detection voltage VS according to the detection voltage VS so as to provide a feedback electrostatic force to the MEMS sensor 10
Implementation Method 3
a cancellation voltage generation circuit used for generating a gravity cancellation voltage according to the detection voltage, wherein the gravity cancellation voltage is positive proportional to the gravity acceleration
Data Source
AI summary
The invention discloses a MEMS sensor detection device and a MEMS sensor system, wherein the MEMS sensor detection device comprises: a readout circuit used for analog signal processing of the output signal of the MEMS sensor to generate detection voltage; a cancellation voltage generation circuit used for generating a gravity cancellation voltage according to the detection voltage, wherein the gravity cancellation voltage and the gravity acceleration are in a positive proportional relationship; a selection circuit used for selecting the detection voltage output in a feedback phase and selecting the gravity cancellation voltage output in a gravity cancellation phase, wherein in one detection period, the feedback phase is located after the gravity cancellation phase; and a feedback circuit used for generating a feedback voltage according to the output voltage of the selection circuit, wherein the feedback voltage is in a positive proportional relationship with the output voltage of the selection circuit. The MEMS sensor detection device and the MEMS sensor system disclosed by the invention can cancel the influence of gravity acceleration and improve the sensitivity of the MEMS sensor system.