Piezoelectric MEMS Microphone Sector Electrode Capacitance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing piezoelectric microelectromechanical system (PMMs) with cantilever structures suffer from poor low-frequency roll-off control and lower sensitivity due to residual stress and limited charge collection, while diaphragm structures face fixed output capacitance issues that affect signal-to-noise ratio (SNR).
Innovation Solution
A piezoelectric MEMS microphone with a diaphragm structure divided into sectors, featuring inner and outer electrodes with specific electrical connections and conductive vias to optimize output capacitance and energy collection, allowing for adjustable capacitance matching with circuitry and improved sensitivity and SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a diaphragm structure is used to collect piezoelectric charges at both edge and center, then sensitivity and output energy are improved, but output capacitance becomes fixed and cannot be matched with circuitry
Solution Approach 1:
The diaphragm is divided into multiple sectors (e.g., six sectors) with electrodes in each sector that can be independently connected. This segmentation allows the total capacitance to be adjusted by selecting which sectors are active and how they are connected (series or parallel), while still collecting piezoelectric charges from both the edge and center regions of the diaphragm, thus maintaining high sensitivity.
2Ease of manufacture
If cantilever structures are used in PMMs, then manufacturing is simplified, but low frequency roll off control deteriorates due to residual stress variations
Solution Approach 1:
The diaphragm is divided into multiple sectors with individual electrode connections. This segmentation allows independent control and optimization of each sector's electrical characteristics, enabling better control over low-frequency roll-off by adjusting which sectors are active and their connection configuration, while maintaining the simple diaphragm structure.
3Ease of manufacture
If cantilever structures are used in PMMs, then manufacturing is simplified, but sensitivity decreases due to limited piezoelectric charge collection at the edge only
Solution Approach 1:
The diaphragm is divided into multiple sectors with electrodes positioned to collect piezoelectric charges from both the edge and center regions. This segmentation enables comprehensive charge collection across the entire diaphragm surface while maintaining structural simplicity, thereby improving sensitivity without complicating manufacturing.
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 enhances sensitivity and signal-to-noise ratio by optimizing electrode connections and capacitance, addressing the limitations of fixed capacitance in diaphragm PMMs and improving low-frequency roll-off control.
Implementation Method 1
a diaphragm including a piezoelectric material attached to the support substrate and configured to deform and generate an electrical potential responsive to impingement of sound waves on the diaphragm
Data Source
AI summary
A microelectromechanical system microphone includes a piezoelectric diaphragm, upper inner electrodes and upper outer electrodes disposed on an upper surface of the diaphragm, and lower inner electrodes and lower outer electrodes disposed on a lower surface of the diaphragm. The diaphragm is divided into a plurality of sectors, a first of the sectors including an inner and an outer upper electrode physically disconnected from an inner and an outer upper electrode on a second sector adjacent to the first sector, and an inner and an outer lower electrode physically disconnected from an inner and an outer lower electrode on the second sector. A first via extends between and electrically couples the upper and lower inner electrodes of the first sector and a first bond pad. A second via extends between and electrically couples the upper and lower outer electrodes of the second sector and a second bond pad.