Acoustic Transducer Split Membrane Design Wide Dynamic Range
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Solution Overview
Problem
Conventional microphones face challenges in achieving a wide dynamic range and low signal-to-noise ratio due to variations and mismatching in acoustic characteristics among multiple sensors, leading to harmonic distortion and reduced sensitivity, especially when detecting both high and low sound pressure levels.
Innovation Solution
The acoustic transducer employs a split membrane design where the vibrating and fixed electrodes are divided into multiple electrodes, forming multiple variable capacitors between the same membrane, which reduces variations in detection sensitivity and mismatching in acoustic characteristics, allowing for improved detection of sound waves across a wide dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple acoustic sensors with different sensitivities are used, then the detectable sound pressure level range is extended, but variations and mismatching in acoustic characteristics occur between sensors
Solution Approach 1:
The acoustic sensor is segmented into multiple divided electrodes (first and second divided electrodes) on the same membrane, each forming a separate variable capacitor. This segmentation allows the sensor to detect different sound pressure levels simultaneously while maintaining consistent acoustic characteristics since all electrodes are on the same membrane with identical physical properties.
Solution Approach 2:
Multiple variable capacitors are combined on a single membrane structure, merging the detection functions of multiple sensors into one unified acoustic sensing element. This merging eliminates variations between separate sensors while maintaining the ability to detect different sound pressure levels through the different capacitance values of the combined capacitors.
2Measurement precision
If detection sensitivity is increased, then small sound waves are detected with high quality, but harmonic distortion increases and maximum input sound pressure decreases
Solution Approach 1:
Different regions of the membrane are assigned to different divided electrodes with different capacitance values. The first divided electrode has a first capacitance value optimized for detecting small sound waves with high sensitivity, while the second divided electrode has a second capacitance value optimized for detecting large sound waves with low distortion. This local quality differentiation allows each electrode to operate in its optimal range.
Solution Approach 2:
The system dynamically selects or combines signals from different divided electrodes based on the input sound pressure level. For small sounds, the high-sensitivity electrode is used; for large sounds, the low-distortion electrode is used. This dynamic adaptation allows the microphone to maintain high detection sensitivity for small sounds while avoiding harmonic distortion for large sounds.
3Adaptability or versatility
If multiple independent acoustic sensors are provided on a single chip, then the detectable sound pressure level range is extended, but variation between chips and mismatching in the chip occur
Solution Approach 1:
Multiple variable capacitors are merged onto a single membrane structure rather than using independent sensors on the chip. This merging ensures that all capacitors are subject to the same manufacturing conditions and physical environment, eliminating variations between chips and mismatching within the chip while still providing different detection sensitivities through different capacitance values.
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 configuration enhances the microphone's ability to detect both high and low sound pressure levels with reduced harmonic distortion, improving the signal-to-noise ratio and expanding the detectable sound pressure range while simplifying the manufacturing process and reducing parasitic capacitance.
Implementation Method 1
detecting a sound wave according to changes in capacitances between the vibrating electrode and the fixed electrode
Implementation Method 2
The acoustic transducer includes a substrate; a vibrating membrane provided above the substrate, including a vibrating electrode; and a fixed membrane provided above the substrate, including a fixed electrode
Data Source
AI summary
The present disclosure is directed to an acoustic transducer configured to detect a sound wave according to changes in capacitances between a vibrating electrode and a fixed electrode. At least one of the vibrating electrode and the fixed electrode being divided into a plurality of divided electrodes, and the plurality of divided electrodes outputting electrical signals. The disclosure includes a digital interface circuit coupled to the divided electrodes. The circuit includes a recombination stage, which supplies a mixed signal by combining the first digital processed signal and the second digital processed signal with a respective weight that is a function of a first level value of the first processed signal. An output stage is included, which supplies, selectively and alternatively, a first processed signal, a second processed signal, or a mixed signal.