The new generation MEMs microphone offers an unlimited audio experience

Tram Ho

The initial feasibility study on capacitive-sensing MEMS microphones at Infineon Technologies AG dates back to 1998, more than two decades ago. At that time, this study was mainly for applications in cars. In the following years, the research and development activities expanded further with the production of silicon-coated micro molds using single-shield technology. But a real breakthrough came in 2012 when Infineon introduced dual shield technology, enhancing the performance of the digital MEMS (Micro Electro Mechanical System) microphones with integrated conductive parameters. market leader.

MEMS microphones have the advantage of providing high audio performance, small size, reasonable cost and low power consumption. Therefore, the MEMS series of microphones has become a preferred choice over the conventional ECM (Capacitor Microphone Using Electret Material). The MEMS microphone also has the advantage of reliability due to its high heat resistance and manufacturing advantages with standard printed circuit board (PCB) assembly and reflux welding techniques.

The growth of smart cell phones is still a key driver of the rapid growth of the MEMS microphone market. However, in recent years, the application has been extended to voice-assisted interface use cases including smart speakers, headphones, wearables, remote controls, laptops, electronic equipment used in cars, in the medical and consumer sectors.

Micrô MEMs thế hệ mới mang tới trải nghiệm âm thanh không giới hạn - Ảnh 2.

User communicates using smart speaker with microphone strip

Today, in most audio devices we see more than one microphone. For example, a smartphone has 2-4 microphones, a smart speaker has 5-7 microphones, and a headset has 4-6 microphones. MEMS microphones make a difference with the deviation between the performance of exceptionally low microphones.

Microphone selection and microphone performance requirements are highly dependent on the use case. For example, a smart speaker placed on a living room table needs to capture 360 ​​° sound and locate the user who is speaking a keyword. After the microphone detects a keyword, the signal processing produces an acoustic beam that captures only the user’s speech and handles ambient noise. For such use cases, phase compatibility and the sensitivity between the microphones are of paramount importance. In the case of mismatches or performance mismatches between the mics, there is a high chance that the smart speaker will not be able to accurately locate the user, resulting in a beam of sound in the wrong direction. This makes users feel uncomfortable to have to repeat keywords and commands many times before the smart speaker can understand them correctly.

Another example of an application is the headset. TWS – True Wireless Stereo headphones or earbuds are in a strong phase of development from a market demand perspective. These devices can use up to 3 MEMS microphones per ear (i.e. 6 microphones per set). The main use of this app is to isolate noise from the environment for a more enjoyable listening experience. This requires the microphone to be small due to space constraints and extreme audio performance in order to pick up noise that can be eliminated.

Micrô MEMs thế hệ mới mang tới trải nghiệm âm thanh không giới hạn - Ảnh 3.

TWS headphones with 2-3 mic in each ear function to reduce background noise

High-quality microphones must simultaneously receive a quality voice signal and help eliminate recording noise, providing a more enjoyable listening experience for the user. But there is no microphone solution suitable for all different applications. Designers must carefully select the most suitable microphone type for the intended use of the product after considering important parameters, namely signal-to-noise ratio, dynamic range, sensitivity, total harmonic distortion, amplitude / phase compatibility.

Infineon provides a standard rating panel that can be used easily with the Arduino and Raspberry Pi platforms for building a quick demo. Available at https://www.infineon.com/cms/en/product/sensor/mems-microphones/

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Source : Genk