A MEMS (Micro-Electro-Mechanical Systems) microphone array is a device that consists of multiple MEMS microphones integrated onto a single substrate or chip. It is designed to capture sound from different directions and is commonly used in various applications, such as beamforming, noise cancellation, and spatial audio recording. The operation of a MEMS microphone array involves several key steps:
Microphone Sensor: Each MEMS microphone in the array consists of a tiny diaphragm that vibrates in response to incoming sound waves. These diaphragms are typically made of a thin, flexible material and are microfabricated on the silicon substrate.
Sensing Principle: The MEMS microphones operate based on the capacitance variation principle. When sound waves strike the diaphragm, it causes it to move, leading to a change in the gap between the diaphragm and a fixed backplate. This variation in distance changes the capacitance between the diaphragm and the backplate.
Signal Conversion: The varying capacitance is converted into an electrical signal through the use of integrated electronics on the same chip. The integrated circuitry typically includes a charge amplifier or a voltage-to-frequency converter that transforms the capacitance variations into electrical signals.
Signal Processing: The electrical signals from each MEMS microphone are processed by the system's signal processing unit. The processing unit can apply different algorithms, such as beamforming or noise cancellation, to improve the performance of the array in specific applications.
Beamforming: Beamforming is a key technique used with MEMS microphone arrays. By combining the signals from multiple microphones in a controlled manner, the array can selectively enhance sound coming from a specific direction while suppressing noise and interference from other directions. This allows the array to focus on a particular sound source and improve the signal-to-noise ratio.
Array Geometry: The physical arrangement of the microphones on the chip is essential to the array's functionality. Different geometric layouts, such as linear, circular, or planar configurations, can be used to achieve various beamforming patterns and directional sensitivity.
Output: The final output of the MEMS microphone array is a set of audio signals, which represent the sound captured from different directions. These signals can be further processed by audio devices or systems for specific applications, such as voice recognition, spatial audio recording, or noise reduction.
In summary, a MEMS microphone array combines the outputs of multiple MEMS microphones to improve the sensitivity, directionality, and overall performance compared to a single microphone. This enables a wide range of applications in audio processing and enhances the quality of sound capture and reproduction in various devices and systems.