MEMS Microphone and Pressure Sensor Integration
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Solution Overview
Problem
Current microphones do not effectively detect both alternating current (AC) and direct current (DC) pressure signals due to their design, which results in user dissatisfaction as they only respond to AC signals and not to ambient pressure changes.
Innovation Solution
An integrated acoustic assembly that combines a microelectromechanical system (MEMS) microphone with a pressure sensor, allowing the microphone to detect both AC and DC pressure signals by using a barometric release mechanism and an enclosed back volume for pressure sensing, eliminating the need for direct access to the ambient environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pierce is added to the diaphragm for pressure equalization, then microphone sensitivity stability is improved, but the ability to detect DC and slowly varying pressure signals is lost
Solution Approach 1:
The invention divides the pressure sensing function into two separate components: the MEMS microphone diaphragm handles AC acoustic signals, while a separate piezoresistive pressure sensor handles DC and slowly varying pressure signals. This segmentation allows each component to optimize its performance for its specific function without the trade-offs that would result from combining them in a single diaphragm structure.
Solution Approach 2:
The invention introduces a separate piezoresistive pressure sensor as an intermediary component to detect DC and slowly varying pressure signals that the MEMS microphone cannot detect. This intermediary sensor works in conjunction with the microphone, with both components reading their respective signals to the same processor, thereby expanding the overall system's pressure detection capabilities without compromising the microphone's AC signal performance.
2Measurement precision
If the microphone is enclosed in a housing with a sealed back volume, then acoustic signal detection is improved, but direct access to ambient pressure for DC signal detection is lost
Solution Approach 1:
The invention merges the enclosed MEMS microphone structure with a separate piezoresistive pressure sensor into a single integrated package. The microphone maintains its sealed back volume for optimal AC acoustic detection, while the pressure sensor is positioned to sense ambient pressure through a separate pathway, allowing both functions to coexist in one device without compromising either performance.
Solution Approach 2:
The integrated acoustic assembly achieves multi-functionality by combining the MEMS microphone and piezoresistive pressure sensor in a single package. This universal design allows the device to perform both AC acoustic signal detection and DC ambient pressure sensing, eliminating the need for separate components and reducing overall system complexity while expanding functional capabilities.
3Adaptability or versatility
If separate AC and DC pressure sensors are used, then comprehensive pressure detection is improved, but device complexity and cost increase
Solution Approach 1:
The invention merges the MEMS microphone and piezoresistive pressure sensor into a single integrated acoustic assembly package. Both sensors read their signals to the same processor, and the assembly is enclosed in a single housing with a unified back volume, thereby reducing structural complexity and eliminating the need for separate mounting and signal processing infrastructure that would result from using completely separate components.
Solution Approach 2:
The integrated acoustic assembly achieves multi-functionality by combining AC acoustic detection and DC pressure sensing in one device. This universal design reduces overall system complexity by eliminating redundant components and simplifying the bill of materials, while also reducing PCB real estate and assembly steps compared to implementing separate AC and DC pressure sensing systems.
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
Enables the detection of both acoustic energy and ambient pressure changes, providing a single packaged device for consumer electronic applications that saves cost and space by integrating sensors and electronics.
Implementation Method 1
sound energy traverses through the port, moves the diaphragm and creates a changing potential of the back plate, which creates an electrical signal
Implementation Method 2
The pressure sensor is configured to sense a pressure of the back volume
Implementation Method 3
a pierce in the diaphragm that allows for pressure equalization between the back volume and the ambient environment
Data Source
AI summary
The present disclosure generally relates to acoustic assemblies. One acoustic assembly includes a base and a first die disposed on the base. The first die comprises a microelectromechanical system (MEMS) microphone that includes a first diaphragm and a first back plate. The MEMS microphone has a barometric release. The acoustic assembly also includes a second die disposed on the base. The second die comprises a pressure sensor. The acoustic assembly further includes a cover coupled to the base and enclosing the first dies and the second die. A back volume is formed between the base, the first die, the second die, and the cover. The pressure sensor is configured to sense a pressure of the back volume.