FATRI first released the first piezoelectric MEMS speech accelerometer in China

From:    未知 Time:    2021-05-19

Recently, FATRI MEMS piezoelectric speech acceleration sensor was first released in China. 

As an IDM chip enterprise integrating chip design, manufacturing, packaging and testing in the field of MEMS in China, the action frequency of FATRI is frequent. The MEMS piezoelectric speech acceleration sensor released in this paper can effectively filter out environmental noise, not only output single-ended analog, but also pick up high-frequency broadband voice. In addition, it is simple structure, small size, light weight, more convenient installation.

This piezoelectric voice acceleration sensor, which is packaged in a small size of 2.8 mm * 2.6 mm * 0.9 mm, can be integrated into wearable and wearable devices such as TWS headphones. With the annual output value of 150 billion global TWS headphones in the industrial chain, it will usher in a new round of growth in the acoustic industry chain.

Schematic diagram of FATRI MEMS speech accelerometer in headphones

Piezoelectric acceleration sensor, also known as piezoelectric accelerometer, is also an inertial sensor. It uses the piezoelectric effect of certain substances such as quartz crystal. When the accelerometer is vibrated, the force added to the piezoelectric element by the mass block also changes.  When the measured vibration frequency is much lower than the natural frequency of the accelerometer, the change of force is proportional to the measured acceleration.

Main performance parameters of piezoelectric accelerometer :

① Sensitivity.  Piezoelectric acceleration sensor can be regarded as both a charge source and a voltage source, so its sensitivity can be expressed by charge sensitivity and voltage sensitivity respectively.  For a piezoelectric acceleration sensor with a given piezoelectric material, its sensitivity increases with the increase of the mass block.  The piezoelectric speech accelerometer developed by FATRI has a sensitivity of -45 ± 1dBV / g and a resonant frequency of ≤ 3kHz. It can achieve high sensitivity in a small size of 2.8mm * 2.6mm * 0.9mm.

② Frequency response range. According to the analysis of the response condition of inertial accelerometer, the upper limit of using frequency of accelerometer depends on its resonance frequency. The measurable lower bound frequency of piezoelectric acceleration sensor does not depend on the sensor itself, but on the low-frequency characteristics of the measurement system. The charge produced by piezoelectric elements is very weak, and the measurement system inevitably produces charge leakage, which causes measurement error.

The key is to measure such a weak charge ( or voltage ), and how to reduce the charge leakage to the limit required by the measurement accuracy, the charge amplifier is very important.  FATRI have the ability to independently develop charge amplifier chip. The charge amplifier chip can be integrated with the piezoelectric MEMS speech acceleration sensor to match the dedicated digital signal processor ( DSP ) to achieve high fidelity audio signal acquisition.

With the continuous improvement of TWS headphone use experience, call noise reduction will become a trend. At present, the mainstream solution of call noise reduction function is realized by multi-microphone cooperation in hardware and software level.  A variety of main chip companies continue to launch Bluetooth real wireless headphones, prompting the explosion of TWS headphones. FATRI can provide self-developed Bluetooth DSP chip with active noise reduction technology. This Bluetooth chip combines with piezoelectric MEMS speech accelerometer to form a voice solution for FATRI, which can help TWS headphones to achieve high-definition pick-up and comfortable noise reduction in complex real environments.

Except for TWS headphones,  FATRI voice solution can also be applied to AR and VR fields.

As a domestic chip enterprise operating in IDM mode, FATRI has advanced MEMS, ASIC, CPU chip and sensor design, manufacturing, packaging and testing capabilities.FATRI has branches in Beijing, Shanghai, Shenzhen, Xi’an, Xiamen, Quanzhou, France and the United States. More than 45 % of its employees are scientific research personnel. The core R & D personnel are from the world’s top 500 first-line semiconductor companies, such as TSMC, Bosch, Riza and Samsung. FATRI hopes to promote the development of downstream applications through continuous technological innovation, and is committed to providing advanced sensing solutions for smart phones, computers, wearable and IoT devices.