Capacitive MEMS Microphone Diaphragm Static Deflection Non-Linearity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Traditional capacitive MEMS microphones face challenges in reducing overall non-linearity, which affects their performance in terms of Total Harmonic Distortion (THD) and Acoustic Overload Point (AOP).
Innovation Solution
The proposed solution involves a capacitive MEMS microphone design where the diaphragm has a greater static deflection, with a ratio of static effective displacement to thickness greater than or equal to 0.5, which counteracts the non-linearity caused by capacitance detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the diaphragm is configured to have great stiffness, then the diaphragm has low static deflection and mechanical linear performance is ensured, but the diaphragm becomes less sensitive
Solution Approach 1:
The patent changes the static deflection parameter of the diaphragm from the conventional low deflection (W0/t < 0.5) to great deflection (W0/t ≥ 0.5). This parameter change transforms the diaphragm from a stiff, mechanically linear structure to a more compliant structure that achieves better sensitivity while managing non-linearity through the specific deflection range.
2Stability of the object's composition
If the diaphragm has low static deflection, then mechanical linear performance is ensured, but the overall non-linearity of the microphone cannot be reduced
Solution Approach 1:
The patent applies preliminary anti-action by pre-deflecting the diaphragm to a great static deflection position (W0/t ≥ 0.5) before operation. This preliminary positioning creates a mechanical non-linearity that counteracts the electrical non-linearity from capacitance detection, thereby reducing the overall non-linearity of the microphone system.
3Reliability
If the diaphragm has great static deflection, then the overall non-linearity is reduced, but the diaphragm requires different stiffness characteristics
Solution Approach 1:
The patent modifies the stiffness parameter of the diaphragm to enable great static deflection (W0/t ≥ 0.5). This involves changing the mechanical properties of the diaphragm material or structure to achieve the desired deflection characteristics while maintaining operational reliability and reducing overall non-linearity.
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 design significantly reduces the overall non-linearity of the microphone, thereby improving THD and AOP performance, while maintaining sensitivity and acoustic overload point.
Implementation Method 1
under an operating bias, the diaphragm 12 bends toward the back electrode plate 11
Implementation Method 2
capacitive MEMS microphone is in a dual-ends capacitor structure
Data Source
AI summary
Disclosed in embodiments of the present disclosure are a capacitive MEMS microphone, a microphone unit and an electronic device. The capacitive MEMS microphone includes: a back electrode plate; a diaphragm; and a spacer for separating the back electrode plate from the diaphragm, wherein in a state where an operating bias is applied, a ratio of a static effective displacement of the diaphragm relative to a flat position to a thickness of the diaphragm is greater than or equal to 0.5.