Silicon Capacitive Microphone Back Chamber Segmentation
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Solution Overview
Problem
The limited back volume of existing silicon-based capacitive microphones restricts their frequency response, necessitating a solution to enhance sensitivity and Signal-Noise-Ratio.
Innovation Solution
The design incorporates a chamber support that forms a larger back chamber by communicating two chambers, with leakage holes to manage air pressure and protect the microphone, improving sensitivity, frequency response, and Signal-Noise-Ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional PCB with limited back volume is used, then the microphone structure is simple, but the frequency response is insufficient
Solution Approach 1:
The back chamber is segmented into two separate chambers (first chamber and second chamber) that are communicatively connected. This segmentation allows each chamber to be optimized independently while collectively providing a larger effective back volume, resolving the contradiction between limited space and required volume for frequency response.
Solution Approach 2:
The first chamber and second chamber are nested within each other's spatial footprint, with the second chamber positioned below the first chamber. This nesting arrangement maximizes the use of available vertical space, effectively increasing the back volume without expanding the microphone's overall footprint.
2Reliability
If the back chamber volume is increased, then sensitivity and frequency response are improved, but the device complexity increases
Solution Approach 1:
The chamber support structure serves multiple functions: it provides mechanical support for the MEMS transducer unit, forms the boundary of the first chamber, creates the communication passage between chambers, and supports the leakage holes. This multi-functionality increases sensitivity and frequency response while minimizing the increase in device complexity.
3Reliability
If air is sealed in the back chamber, then pressure reference is maintained, but air expansion from heat or vibration may damage the microphone
Solution Approach 1:
The leakage holes provide a feedback mechanism that allows excess air pressure to escape from the back chamber. When air expands due to heat or vibration, the pressure increase is detected by the system, and the leakage holes automatically release the excess pressure, preventing damage while maintaining normal pressure reference stability during operation.
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 enlarged back chamber significantly enhances sensitivity and frequency response while allowing air leakage to protect the microphone, improving overall performance.
Implementation Method 1
a plurality of leakage holes communicating the first chamber with the receiving space... expanded air can be leaked to the outside through the leakage holes
Data Source
AI summary
A silicon based capacitive microphone includes a printed circuit board, a shell mounted on the printed circuit board and forming a receiving space together with the printed board, a chamber support located on top of the printed circuit board and received in the receiving space, a transducer unit and a controlling chip respectively mounted on the chamber support, wherein the chamber support forms a first chamber together with the printed board, the chamber support includes an opening, the transducer unit is provided with a second chamber and covers the opening, the second chamber communicates with the first chamber via the opening.