6 May 2012

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A new acoustic sensor technology has been developed which is much more immune to mechanical vibration, temperature variations, and electromagnetic interference while providing high-fidelity reproduction of audio signals with very low power consumption.

ST Microelectronics has teamed up with Omron Corporation to produce the new MP34DB01 digital MEMS microphone, which integrates ST's electronic control circuit and Omron Corporation's micro-machined sensor in a single package.

The MP34DB01 is an omni-directional sound-sensing device with a built-in capacitive sensing element and an IC interface with stereo operation capability. Omni-directional sensitivity improves sound quality by detecting and filtering out background noise.

This device is the first top-port digital MEMS microphone with better acoustic parameters than bottom-port microphones.

A new patentable top port technology enables the microphone membrane to be placed closer to the acoustic port hole on the top of the package and still provide a substantial increase in performance with the same size package.

It is the first microphone ever to be is equipped with a top-port sound-inlet with a signal-to-noise (SNR) ratio of 63 dB and a flat frequency response in the audio band of 20-20,000 Hz.

The acoustic sensing element is made using a special silicon micromachining process designed to produce audio sensors. The IC interface is manufactured using a CMOS process that allows designing a dedicated circuit able to provide a digital signal externally in PDM format.

The MP34DB01 has an acoustic overload point of 120 dBSPL with a very high 62.6 dB signal-to-noise ratio and -26 dBFS sensitivity. It is contained in a SMD-compliant, EMI-shielded package and has an extended temperature range from -30 °C to +85 °C.

These features make the microphones perfect for applications like speech-recognition systems, where speech is used to control software applications or other types or voice activated actuators.

This microphone would also work well in noisy industrial applications, where the high signal-to-noise ratio and dynamic range make them ideal for devices like phonometers.

With its low power requirements and tiny 3x4x1 mm package, the device has a huge potential in consumer applications like cell phones, tablets, media player, video cameras, or other applications where small size, high sound quality, reliability, and affordability are critical factors.

Multiple microphones can be used in the same device and set up in an array to increase the filtering levels and provide even better sound quality. The Smart Voice audio processors within the device make use of the enhanced capabilities of ST’s digital MEMS microphones in multi-microphone arrays, enabling features like acoustic echo cancellation, noise suppression, or beam-forming, which is a sound-processing technique that helps isolate a sound and its location.