Triple-Membrane MEMS Capacitor Assembly for Noise Reduction
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Solution Overview
Problem
Existing MEMS silicon microphones face challenges in reducing ASIC noise, and there is a need to increase the capacitance to meet evolving requirements.
Innovation Solution
A triple-membrane MEMS device is configured with a first, second, and third membrane, along with stators, to form capacitors in series or parallel configurations, enhancing motor sensitivity or reducing output impedance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a sealed dual-membrane MEMS structure is used, then noise reduction is improved, but capacitance is insufficient to further reduce ASIC noise
Solution Approach 1:
The single capacitor structure is segmented into four separate capacitors (C1, C2, C3, C4) formed by three membranes and two stators. This segmentation allows each capacitor to contribute to the total capacitance while maintaining the sealed dual-membrane noise reduction benefits, thereby increasing overall capacitance without compromising noise performance.
Solution Approach 2:
The patent employs a nested structure where three membranes are arranged in sequence with stators positioned between them, creating multiple capacitor elements within a single integrated package. This nesting approach maximizes capacitance within the constrained physical space while preserving the compact sealed design that reduces noise.
2Object-affected harmful factors
If more capacitance is added to reduce ASIC noise, then noise performance is improved, but device complexity increases
Solution Approach 1:
Multiple capacitor-forming elements (membranes and stators) are merged into a single integrated MEMS device package. The three membranes and two stators work together as one unified structure, achieving increased capacitance for ASIC noise reduction without requiring separate discrete components, thus limiting the increase in overall device complexity.
Solution Approach 2:
The additional membranes and stators serve dual purposes: they increase capacitance to reduce ASIC noise while simultaneously maintaining the sealed acoustic isolation structure. This multi-functionality allows the device to achieve noise reduction without proportionally increasing complexity.
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 configuration increases motor sensitivity or reduces output impedance, effectively addressing ASIC noise and improving the performance of MEMS microphones.
Implementation Method 1
The movement of the membrane relative to the fixed plate varies the distance between the membrane and the fixed plate of the variable capacitor, which in turn varies the capacitance of the variable capacitor. The variation of the capacitance is determined by various parameters of the acoustic pressure wave
Data Source
AI summary
A triple-membrane MEMS device includes a first membrane, a second membrane and a third membrane spaced apart from one another, wherein the second membrane is between the first membrane and the third membrane, a sealed low pressure chamber between the first membrane and the third membrane, a first stator and a second stator in the sealed low pressure chamber, and a signal processing circuit configured to read-out output signals of the triple-membrane MEMS device.