For anyone who watched cop or spy TV dramas from the 1960s, the idea of wearing a bug or bugging something with a tiny microphone always gets your attention. Is the microphone in the person's lapel (like a wearable)? Is it in the flower pot?
Today, small microphones are still being developed, and manufacturers are finding new ways to engineer them using micro-electromechanical system (MEMS) technology. As always, the idea is to keep them discrete.
MEMS technology is described as a miniature machine that has both mechanical and electronic components. MEMS-based devices can be small as several millimeters to less than one micrometer, which is many times smaller than the width of a human hair.
Designers of digital devices on a consumer or industrial level use MEMS microphones for the growing selection of Internet of Things devices and automotive and other space-constrained applications, particularly sensors. MEMS devices also can provide designers with low power and small form factor options while delivering high audio quality.
In this week's New Tech Tuesdays, we'll check out compact and low-power consumption MEMS microphones from TDK InvenSense, STMicroelectronics, and CUI Devices.
The TDK InvenSense T3903 Multi-Mode Microphone enables the transition of sound from analog to a digital output. The T3903 supports always-on mode applications in smartphones, tablets, remote controls, smart TVs, Bluetooth® headsets, and digital still/video cameras. The T3903 is a bottom-port pulse-density modulation microphone. The microphone won't completely dose off: It goes into sleep mode when the clock frequency falls below 200kHz and starts up in 7ms.
The STMicroelectronics IMP23ABSU MEMS Microphone features a capacitive sensing element and an integrated circuit interface that makes it capable of detecting acoustic waves. The sensing element is manufactured using a specialized silicon micromachining process to produce audio sensors. It's ideal for use in conditioning monitoring of industrial equipment, leak detection, electrical arching, smart medical instruments, wearable and hearable devices, smart speakers, and active noise-canceling headsets.
CUI Devices I²S MEMS Microphones are a little different in that they have top and bottom port versions. The microphones also have a low current draw, simple design, and reduced vibration sensitivity. They feature omnidirectional directivity with analog, digital PDM, or digital I²S output types and are reflow solder compatible. The microphones are used in a range of portable consumer electronics, including smartphones, tablets, smart home devices, and more.
MEMS microphones have evolved in IoT, mobile, and automotive applications. Sales of MEMS-based pressure sensors, microphone chips, accelerometers, gyroscope devices, and actuators are expected to increase annually by double-digit percentages until 2024, according to IC Insights Analysis. Yes, discrete microphones have come a long way since their days as spying devices worn on your lapel.
Tommy Cummings is a freelance writer/editor based in Texas. He's had a journalism career that has spanned more than 40 years. He contributes to Texas Monthly and Oklahoma Today magazines. He's also worked at The Dallas Morning News, Fort Worth Star-Telegram, San Francisco Chronicle, and others. Tommy covered the dot-com boom in Silicon Valley and has been a digital content and audience engagement editor at news outlets. Tommy worked at Mouser Electronics from 2018 to 2021 as a technical content and product content specialist.