STMicroelectronics’ advanced vibration sensor eliminates road noise for quieter cabins in the electric vehicle era

As a first-class MEMS automotive accelerometer, AIS25BA is optimized for road noise and related vibrations, and can accurately control the in-car acoustic environment, making the cabin quieter.

China, October 17, 2022 -- STMicroelectronics (ST), a global semiconductor company serving multiple electronic applications and ranked first in the world, has launched a new road noise cancellation (RNC) MEMS sensor. The new product uses active noise control (ANC) technology to reduce road noise, making the car more comfortable and quiet. In the past, engine performance, exterior design and transmission were the three defining factors of a car; now, drivers and passengers are paying more and more attention to driving comfort.

Electric vehicles (EVs) are quieter than fuel-powered vehicles (ICEs), which is an inherent advantage of electric vehicles. Automakers are therefore focusing on reducing the noise caused by wheels or vibrations in the car, creating a quieter cabin environment so that passengers can better enjoy the fun of travel.

The noise reduction algorithm cooperates with the sensor array installed in various parts of the vehicle to measure the ambient sound and use the noise reduction waveform to reduce the vibration noise (reduction) to achieve the purpose of eliminating vibration noise.

“In today’s digital age, the smart way to deal with unwanted sounds in a car is to mute them rather than reduce them, in order to ensure a quieter cabin and safer, more pleasant journeys,” said Simone Ferri, Marketing General Manager, MEMS Division, Analog, MEMS & Sensors Group, STMicroelectronics. “As vehicles transition to hybrid and electric vehicles, the impact of road noise can be significant, and our AIS25BA accelerometer brings great value to system designers.”

STMicroelectronics has used its research and development capabilities in micro-electromechanical systems (MEMS) ICs to give the AIS25BA excellent product features, allowing RNC systems to have higher accuracy. The sensor's electrical noise is currently the lowest on the market, helping automotive engineers achieve a quieter in-car environment. On the other hand, it has the fast response/low latency required for the RNC system to calculate the correction waveform in real time, as well as the high bandwidth required to capture interference across the entire audio frequency range relevant to the application. The wide operating temperature range and mechanical resistance to variation allow the sensor to be placed in the harshest places in today's vehicle environment: near the engine or drive motor, and close to the wheels and suspension.

Technical Supplementary Information

STMicroelectronics' AIS25BA 3-axis accelerometer is designed with RNC system accuracy as a priority. The noise density is very low, 30µg/√Hz for both X and Y axes and 50µg/√Hz for Z axis, which is 58% lower than the closest competitor.

In addition to the excellent noise performance, the frequency response extends to second order, thus covering the entire frequency spectrum relevant for in-cabin noise reduction. Likewise, the total sensor latency of 266µs gives the system plenty of time to generate the noise reduction signal in real time.

In addition, the sensor has a time-division multiplexed (TDM) digital interface that allows the system to synchronize multiple accelerometer outputs to measure the vibration noise of the entire vehicle. This audio-friendly interface can also be easily connected to other types of data buses widely used in automobiles. The full-scale measurement range is selectable, with a maximum range of ±7.7g, which provides ample margin relative to the typical strong vibration in automotive use. The power supply voltage range is 1.71V to 1.99V.

The AIS25BA is AEC-Q100 qualified and is available in a 14-pin 2.5mm x 2.5mm x 0.86mm LGA package. Please contact your local ST sales office for sample requests.