MEMS Microphone Differential Sensing Single Backplate
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Solution Overview
Problem
Existing microelectromechanical microphones with differential capacitive sensing require complex structures and multiple backplates, leading to costly and complex manufacturing processes.
Innovation Solution
A microelectromechanical microphone design featuring a movable diaphragm and a single rigid backplate mechanically coupled via dielectric members, allowing for differential capacitive sensing without multiple backplates, enabling simplified fabrication and enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple backplates are used for differential capacitive sensing, then sensing capability is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the functions of multiple backplates into a single backplate structure. The single backplate is mechanically coupled to the diaphragm through flexible members, allowing it to participate in differential capacitive sensing without requiring multiple separate backplate components. This reduces structural complexity while maintaining the sensing capability.
Solution Approach 2:
The single backplate serves multiple functions: it acts as a capacitive electrode for differential sensing, provides mechanical support through rigid portions, and transmits acoustic vibrations through flexible members. This multi-functionality eliminates the need for separate backplate components while achieving the required sensing performance.
2Measurement precision
If multiple backplates are used for differential capacitive sensing, then sensing capability is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple backplate functions into a single manufacturable component. The single backplate with integrated rigid and flexible portions can be fabricated using standard semiconductor processing techniques, simplifying the manufacturing process compared to assembling multiple separate backplate components.
Solution Approach 2:
The backplate is segmented into rigid portions and flexible portions that can be formed in a single fabrication process. This segmentation allows the complex multi-functional component to be manufactured using standard semiconductor techniques while reducing assembly complexity.
3Measurement precision
If complex structures with multiple backplates are used, then differential capacitive sensing is achieved, but device cost increases
Solution Approach 1:
The patent reduces device cost by merging multiple backplate components into a single structure. This reduction in component count decreases manufacturing complexity and material costs while maintaining the differential capacitive sensing capability through the single backplate's flexible member coupling.
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 design reduces fabrication complexity and costs while providing higher sensitivity, fidelity, and shock robustness compared to conventional microphones with more complex arrangements.
Implementation Method 1
The movable diaphragm and the substrate can form a first capacitor that has a first capacitance based on a displacement of the movable diaphragm caused by the acoustic wave. In addition, the backplate and the movable diaphragm can form a second capacitor that has a second capacitance based on the displacement of the movable diaphragm.
Implementation Method 2
a substrate that defines an acoustic port configured to receive an acoustic wave
Implementation Method 3
The backplate can be mechanically coupled to the movable diaphragm via one or more dielectric members. In certain implementations, each of the one or more dielectric members can extend between a surface of the backplate and a surface of the movable diaphragm.
Data Source
AI summary
Microelectromechanical microphones include structures that permit differential capacitive sensing. In certain structures, a movable plate is disposed between a rigid plate and a substrate. A first capacitor is formed between the movable plate and the substrate and a second capacitor is formed between the movable plate and the rigid plate. Respective bias voltages can be applied to the rigid plate and the substrate, and a differential capacitive signal can be probed in response to displacement of the movable plate caused by a pressure wave. The movable plate and the rigid plate are mechanically coupled to first and second portions of the substrate, respectively. A dielectric member mechanically couples the movable plate and the rigid plate, thus providing mechanical stability.