Integrated MEMS Microphone Membrane for Back-Volume Expansion
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Solution Overview
Problem
The acoustic performance of micro-electromechanical systems (MEMS) microphones is limited by the air volume available in the microphone package, leading to issues such as low sensitivity, high noise ratios, and poor frequency response due to the configuration of front and back volumes.
Innovation Solution
The addition of a membrane to the MEMS microphone package, positioned to block obstructions and increase the back volume, while allowing air to flow through, enhances the acoustic performance by improving sensitivity and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the air volume in the MEMS microphone package is increased, then the acoustic performance and sensitivity are improved, but the device size and complexity increase
Solution Approach 1:
The patent implements nesting by placing the acoustic membrane inside the existing MEMS microphone package structure, specifically within the back volume area. The membrane is positioned between the acoustic port and the MEMS diaphragm, effectively utilizing the internal space without requiring external expansion of the device housing. This nested configuration allows the membrane to contribute to acoustic performance while maintaining compact device dimensions.
Solution Approach 2:
The patent introduces a new spatial dimension by adding the acoustic membrane as a separate layer within the three-dimensional package structure. Instead of expanding the horizontal footprint, the solution utilizes the vertical dimension by stacking the membrane above the MEMS diaphragm and below the package lid, thereby increasing effective air volume without increasing device width or length.
2Reliability
If a membrane is added to block obstructions, then protection of inner components is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent employs a thin film acoustic membrane made of flexible material that can be stretched and sealed across the acoustic port opening. This thin film approach provides effective protection against obstructions and environmental contaminants while maintaining acoustic transparency. The flexible nature of the membrane allows it to conform to the package opening and create reliable seals without requiring complex rigid structures or multiple assembly steps.
3Measurement precision
If the back volume is increased to improve sensitivity, then the signal-to-noise ratio is improved, but the device size increases
Solution Approach 1:
The patent segments the internal volume into distinct functional regions: the front volume for acoustic wave entry, the back volume for enhanced acoustic performance, and the protected internal space for sensitive components. The acoustic membrane acts as a boundary that separates these regions while allowing acoustic energy transfer. This segmentation enables independent optimization of each volume for its specific function without requiring uniform expansion of the entire device.
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 increased back volume facilitates easier movement of the acoustic membrane, resulting in higher sensitivity and lower noise floors, thereby improving the signal-to-noise ratio and frequency response of the MEMS microphone.
Implementation Method 1
a membrane associated with the second port configured to block an obstruction from entering the MEMS package while allowing air to flow through the membrane
Implementation Method 2
A MEMS diaphragm forms a capacitor and sound pressure waves cause movement of the diaphragm
Data Source
AI summary
Systems and methods for a MEMS microphone package are disclosed. The MEMS microphone package may include a first port to direct sound to a MEMS system, including a die substrate, an acoustic membrane, and one or more plates. The MEMS microphone package may include an ASIC to produce microphone output based on an electrical signal, a PCB, a lid, and a second port. The first port and the second port may define a front volume and a back volume respectively. The second port may increase the back volume to improve sensitivity and reduce the acoustic sensor's noise floor to improve signal-to-noise ratio.