MEMS Microphone Gain Control for High SPL and Low Noise
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Solution Overview
Problem
MEMS microphones face challenges in achieving a high Signal-to-Noise ratio and sound pressure level while minimizing power consumption, size, and supply voltage, as existing solutions often conflict in meeting these objectives.
Innovation Solution
A MEMS microphone design incorporating a transducer element, signal processing circuit with adjustable gain settings, and a gain control unit that adjusts the gain of both analog and digital signal processing stages to maintain a linear relationship between input and output signals, preventing overflow and ensuring high sound pressure levels and Signal-to-Noise ratios across varying signal amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gain setting of the first part is increased to improve Signal-to-Noise ratio, then the Signal-to-Noise ratio is improved, but the sound pressure level capability deteriorates due to overflow
Solution Approach 1:
The patent applies dynamic gain control by making the gain settings of the first and second parts adjustable and interdependent. The gain control unit dynamically modifies the gain setting of the first part based on the gain setting of the second part, allowing the system to adapt to different operating conditions and prevent overflow while maintaining high Signal-to-Noise ratio.
Solution Approach 2:
The patent implements a feedback mechanism where the gain control unit monitors the gain setting of the second part and uses this information to adjust the gain setting of the first part. This closed-loop control ensures that the overall gain remains within safe limits while optimizing the Signal-to-Noise ratio for the given operating conditions.
2Reliability
If the gain setting of the first part is decreased to prevent overflow and maintain high sound pressure level, then the sound pressure level capability is maintained, but the Signal-to-Noise ratio deteriorates
Solution Approach 1:
The system dynamically adjusts the gain setting of the first part based on real-time operating conditions and the gain setting of the second part. This allows the system to maintain high sound pressure level capability when needed while optimizing Signal-to-Noise ratio for the given conditions, rather than being fixed at a conservative value.
Solution Approach 2:
The patent changes the gain parameter of the first part based on the operating conditions and the gain setting of the second part. By making this parameter adjustable and interdependent, the system can optimize performance for different scenarios, achieving both high sound pressure level capability and good Signal-to-Noise ratio when required.
3Device complexity
If fixed gain settings are used to simplify the circuit design, then the device complexity is reduced, but the adaptability to different signal amplitudes deteriorates
Solution Approach 1:
The gain control unit serves multiple functions: it prevents overflow by adjusting the first part's gain based on the second part's gain setting, optimizes Signal-to-Noise ratio for different operating conditions, and maintains a linear input-output relationship. This multi-functionality provides adaptability without proportionally increasing complexity.
Solution Approach 2:
The system performs self-adjustment through the gain control unit, which automatically modifies the first part's gain setting based on the second part's gain setting and operating conditions. This self-service mechanism provides adaptability to different signal amplitudes without requiring external control or complex additional circuitry.
Data Source
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AI summary
The present invention concerns a MEMS Microphone (1) comprising, a transducer element (2) for providing an electrical signal, a first part (3) for receiving the electrical signal from the transducer element (2) and for providing a processed signal, a second part (4) for receiving the processed signal from the first part (3) and for providing an output signal of the MEMS microphone (1), and a gain control unit (5) that is enabled to adjust a gain setting of the first part (3) and to adjust a gain setting of the second part (4). Further, another aspect of the present invention concerns a method of operating said MEMS microphone (1) comprising the step of adjusting a gain setting of the first part (3) and adjusting a gain setting of the second part (4).