MEMS Microphones: The Technology of Choice For Today’s Consumer Devices
January 18, 2023
The recent pandemic was the beginning of many trends. One of those was the “work from everywhere” phenomenon, which is here to stay, at least in some form. With the number of home employees jumping in size seemingly overnight, along with it came the need for tools that could accommodate this environment, from video conferencing software to computer hardware.
At the same time, high-quality audio became crucial for employees to stay connected to their work environment through remote access. For the audio experience to come as close as possible as actual encounters, equipment needed to deliver clear, uninterrupted audio signals, even in noisy environments. Features like active noise cancelling (ANC), voice control, and transparent hearing grew in importance to ensure daily business communication ran smoothly in the new “work from everywhere” reality.
Two devices that are now crucial for efficient remote work are laptops and earbuds. To meet the increasing audio requirements of remote work, these devices rely on a combination of sophisticated software and hardware, such as more and better performing microphones. Specifically, both laptops and earbuds rely on MEMS (micro-electromechanical systems) microphones to pick up the voice signals. Today, MEMS microphones have become the technology of choice in consumer electronics devices, delivering high-performance and low power consumption in a small form factor.
Characteristics of MEMS Microphones
The diagram above shows the construction of a typical MEMS microphone. The module contains two chips on a PCB, covered by a lid with an open sound port. The ASIC converts the physical sound pressure measurements of the MEMS die into a digital signal, which will then be transmitted to the device’s codec.
MEMS microphones can be manufactured in large quantities on silicon wafers. This method ensures low part-to-part deviation, meaning extremely reliable production flow.
One of the key advantages of the MEMS microphone is its small size, which is crucial to keeping bulk down while enabling a high level of sound quality and user experience. A second, and no less important characteristic of the MEMS microphone is its low power consumption that delivers an increased battery lifetime for the end device, which is particularly important in today’s remote working environment where users expect long-lasting performance.
High SNR and Low Power
Signal-to-noise ratio (SNR) is a key specification for microphones. It is defined as the ratio between actual the audio signal captured and the self-noise of the microphone. A microphone with a low self-noise (and hereby high SNR) enables recording of the faintest sounds. It also delivers features like ANC or Transparent Hearing for earbuds.
ANC reduces unwanted background noise using microphones. It inverts the soundwaves to create an interference in front of the ear canal, thereby cancelling the background noise. Good ANC performance is essential for remote work, as it allows the user to concentrate even in noisy environments, such as working from a busy home, a café, or an airport. Infineon’s latest microphone IM69D128S is specifically designed for these kinds of applications and offers an SNR of 69 dBA. The digital microphone is based on Infineon’s Sealed Dual Membrane MEMS technology which delivers high ingress protection (IP57) at a microphone level.
In addition to the excellent SNR capabilities, this MEMS microphone is also known for its ultra-low power consumption. The microphone’s reduced power consumption, along with other components like Bluetooth and a DSP codec, help reduce the size of the battery and thus the entire end product. In practice, the battery and speaker could occupy as much as two-thirds of the device’s overall space. In addition, the smaller battery generally makes for a product that’s more comfortable to wear, especially when the ear buds are worn all day.
Today’s wireless earbuds contain up to six microphones, therefore, having microphones that are small in size and low in power without a drop in acoustic performance makes this microphone a perfect fit for many upcoming hearable products.
Infineon’s XENSIV™ MEMS microphones are designed to capture audio with high precision and quality all in a small package. Infineon’s ultra-low power digital MEMS microphone consumes less than 520 μA. It enables crystal clear audio and is based on the company’s Sealed Dual Membrane MEMS technology, which delivers high ingress protection (IP57) at a microphone level.
High SNR MEMS Microphones For Laptops, Too
In addition to earbuds, laptops with high audio quality microphones and speakers are essential for a pleasant working experience. An increasing number of hybrid conference calls push the need for excellent audio performance. By having high SNR microphones already integrated into the laptops, it “frees” the user from the desk, as there is no need for a headset at all. In an office environment, it can also replace common conference speakers, as the laptop can be used as a conference device for a medium-sized group due to excellent far field voice pickup.
Infineon just launched a new microphone, the IM70D122, which boasts comparable features. Also based on the company’s Sealed Dual Membrane MEMS technology, it delivers IP57 ingress protection. In addition, it has an SNR of 70 dB and a high sensitivity, -26 dBFS. Hence, the part is perfectly suited for laptops, tablets, cameras and conference systems, but not limited to these applications.
In summary, through their size and technical characteristics, MEMS microphones enable customers to take their devices to the next level of audio performance. They play a crucial role, delivering high-quality audio in day-to-day business, ensuring a smooth collaboration between all team members, wherever they are. Beyond TWS and laptops, MEMS microphones are revolutionizing and enabling next-generation features in variety of applications, such as smartphones, conference systems, smart home devices, wearables, among others. And thanks to the latest progress in MEMS microphone development, future consumer devices will benefit from even lower power consumption and higher audio performance.