Dual-Cavity MEMS Microphone Packaging for Resonance Equalization
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Solution Overview
Problem
Conventional MEMS microphones face challenges with resonance frequencies within the audio band, leading to potential damage and inaccurate sound reproduction, as existing solutions fail to effectively eliminate or adjust resonance frequencies in real-world environments where noise is unpredictable.
Innovation Solution
The implementation of an electronic device package featuring a primary MEMS microphone and a reference MEMS microphone with different resonance frequencies, both receiving a common acoustic signal for simultaneous transduction, and an equalization module processes the transduced signals to remove resonance peaks, utilizing separate back cavities and signal processing hardware for effective frequency response equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resonance frequency modification through packaging is applied, then resonance frequency can be pushed out of audio band, but this approach cannot adapt to unpredictable real-world noise conditions
Solution Approach 1:
The patent implements dynamic equalization that continuously adapts to changing acoustic environments. The system processes incoming audio signals in real-time and adjusts equalization parameters dynamically, allowing the microphone to maintain optimal performance across varying noise conditions rather than relying on fixed packaging modifications
Solution Approach 2:
The patent employs feedback mechanisms where the output of the reference microphone is used to generate equalization coefficients that are applied to the primary microphone signal. This closed-loop approach allows the system to continuously compensate for resonance and adapt to changing conditions, improving reliability while maintaining adaptability
2Manufacturing precision
If factory calibration with pink noise is used, then fixed frequency notch can be added at resonance frequency, but this cannot compensate for resonance in unpredictable real-world environments
Solution Approach 1:
The patent performs preliminary characterization during manufacturing to identify resonance frequencies, but more importantly, it continuously performs equalization adjustments during operation based on real-time signal processing. This dual approach ensures both manufacturing precision and environmental adaptability
Solution Approach 2:
The system changes equalization parameters dynamically based on the analyzed frequency content of incoming signals. By adjusting equalization coefficients in real-time rather than relying on fixed factory calibration, the system maintains manufacturing precision while adapting to varying environmental conditions
3Reliability
If structural features are added to remove resonance peak, then resonance can be eliminated from audio band, but device complexity increases
Solution Approach 1:
The patent replaces mechanical/structural resonance elimination methods with electronic signal processing. Instead of adding physical features to the microphone structure, the system uses digital equalization algorithms to remove resonance peaks, thereby maintaining simple hardware while achieving reliable resonance removal
Solution Approach 2:
The patent introduces a reference microphone as an intermediary element that captures the acoustic environment without the resonance characteristics of the primary microphone. This intermediary is used to generate equalization coefficients that compensate for resonance in the primary microphone, avoiding direct modification of the primary microphone structure
4Reliability
If multiband processing is applied, then band around resonance can be addressed and extra peaks compensated, but device complexity increases
Solution Approach 1:
The patent focuses equalization efforts specifically on the resonance frequency region rather than applying comprehensive multiband processing across the entire frequency spectrum. By concentrating computational resources on the critical resonance bands, the system achieves effective equalization with reduced processing 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
This approach enhances the sensitivity and signal-to-noise ratio of MEMS microphones without tradeoffs, providing accurate acoustic signal estimation in noisy environments and maintaining high performance by adaptively addressing resonance issues across varying conditions.
Implementation Method 1
Piezoelectric MEMS microphones have been used to address the deficiencies of capacitive MEMS microphones
Implementation Method 2
both the first back cavity and the second back cavity are sealed
Data Source
AI summary
An electronic device package comprises an electronic acoustic device including a primary microphone having a frequency response having a resonance frequency, and a reference microphone having a frequency response including a resonance frequency. The primary microphone and the reference microphone are configured to substantially simultaneously receive a common acoustic signal to produce a transduced signal of the primary microphone and a transduced signal of the reference microphone, the resonance frequency of the reference microphone being different than the resonance frequency of the primary microphone. An equalization module is configured to equalize the frequency response of the microphone based on the transduced signal of the microphone and the transduced signal of the reference microphone. The package defines a first back cavity of the primary microphone and a second back cavity of the reference microphone, the second back cavity being acoustically isolated from the first back cavity.