In order to further lead the development of smart wearables and promote TWS earphones, smart glasses, hearing aids and other products to achieve high performance and thinness, AAC has recently launched SOPRANO, an ultra-small MEMS speaker tweeter unit, with a package size of only 16.2 mm³. This innovative landmark product may be the smallest MEMS speaker unit in the industry at present.
Based on PZT thin film piezoelectric technology, SOPRANO is fabricated with pure MEMS technology and integrates the diaphragm and driver structure. In terms of acoustic performance, SOPRANO features excellent high-frequency extensibility, with the high frequency extended to more than 40 kHz, offering Hi-Res Audio certification and superb sound quality. At the same time, it can achieve hearing assistance in the medical and health field, providing strong support for users with high-frequency hearing loss.
Significantly expanding the Hi-Fi audio range for a new audio experience
The signal path of TWS earphones requires the full cooperation of all its modules to achieve perfect HD audio quality. This includes rich lossless audio sources, Bluetooth transmission technology with lossless audio quality, and multi-unit speakers. Achieving the perfect reproduction of HD audio in a limited space has become a common challenge for major TWS product manufacturers and acoustic solution providers.
Hi-Res HD audio speakers are required to not only cover the frequency range audible to human ears (20 Hz to 20 kHz), but also to expand to the ultrasonic frequency range (20 kHz to 40 kHz), delivering superior audio resolution in the whole frequency range and accurately reproducing the original sound details.
However, due to the inherent system architecture, current TWS products mainly use traditional moving-coil or moving-iron speaker units. The moving coil units’ frequency bandwidth is relatively narrow and its frequency response curve often begins to decline rapidly after 14 kHz, failing to meet the requirements of Hi-Res Audio certification. The moving iron units’ shape and size make it difficult to stack in TWS earphones. AAC MEMS speakers with remarkable high-frequency performance can effectively make up for the deficiencies of traditional solutions in high frequency performance and dimensions, and complement low-frequency moving coil units to form a perfect full-frequency combination, which significantly expands the Hi-Fi audio range and enables TWS earphones to achieve more loudness.
AAC SOPRANO: Enhancing the TWS acoustic experience and design
After several rounds of iterative optimization in design and technology, AAC SOPRANO perfectly meets the application requirements of TWS earphones in terms of product form, size, performance and reliability, which can provide TWS product manufacturers with more flexibility and convenience in earphone design, stacking and assembly, and provide a higher-quality audio experience for users.
1. Ultra-small and easy to stack
SOPRANO features a hexagonal design, with a diameter of 5 mm, a thickness of only 1 mm, and a weight of only 23.5 mg. SOPRANO is far lighter and thinner than traditional and similar products on the market. Compared with the traditional rectangular product design, SOPRANO can be flexibly arranged in the front cavity of TWS products, providing them with superior ergonomics. At the same time, SOPRANO can be modularized and integrated with AAC’s self-developed high-performance FB MIC (feedback microphone) dedicated for TWS to form an integrated solution.
Thanks to the MEMS technology and superior design, SOPRANO achieves an ultra-small and lightweight design. Compared with the traditional tweeter unit, it saves nearly 75% of the space in TWS earphones. This provides TWS product manufacturers with great convenience and expandability for stacking and effectively provides users with a more comfortable experience.
2. Outstanding sound performance without a power amplifier
In order to reach the technical specifications of sound pressure level (SPL) required by TWS application scenarios, existing piezoelectric MEMS speakers on the market need an additional dedicated PA chip to maintain a large drive voltage. However, using PA chips occupies more stacking space and consumes more static power, which is obviously contrary to the trend of miniaturization and low power consumption of TWS devices.
SOPRANO can easily achieve an SPL ≥ 100 dB @ 6 kHz to 40 kHz with a driving voltage of 1 Vrms. This technical breakthrough enables the Hi-Fi tweeter to achieve high-fidelity and high-frequency audio through the existing TWS earphone Bluetooth chip without a PA, making it easier to apply the new MEMS speaker technology.
3. Fast response and high phase uniformity
Thanks to the MEMS structure design and semiconductor process capability, SOPRANO boasts fast response and uniformity of SPL (±1 dB) and phase (±1°), which effectively meets the requirements of end users for spatial audio and left-right ear balance, and realizes fast and accurate 3D panoramic surround sound. This feature helps TWS product manufacturers greatly simplify the assembly, screening and calibration of the left and right earphones, optimizing the manufacturing process of the production line, improving production efficiency and reducing overall costs.
4. Low power consumption and long-lasting battery life
Endurance has always been a pain point of wearable devices. Multifunctional integration and experience improvement entails higher standards for the power consumption of devices. SOPRANO is manufactured with pure MEMS technology, and the power consumption of the MEMS chip is only 50 μW. Its performance in terms of power consumption is outstanding. Moreover, AAC’s self-developed high-sensitivity SOPRANO without a PA perfectly adapts to the mature Bluetooth conditions in the industry, greatly improving the service life of TWS devices and guaranteeing their long-lasting battery life.
5. Self-developed “flip-chip-like” technology with high reliability
Different from the package scheme of patch and wire bonding used by similar products in the industry, SOPRANO uses the “flip-chip-like” package process developed in-house by AAC, which achieves high reliability while maintaining high performance and an ultra-small package size. At present, SOPRANO has passed all environmental and mechanical reliability assessment tests, as well as the sweat test, with an IP58 waterproof and dustproof grade, and can resist 10 kg mechanical impacts.
6. Fully automatic manufacturing with higher production efficiency
In terms of scale manufacturing, SOPRANO’s high-temperature-resistant reflow soldering can be integrated into the SMT automatic manufacturing process. Compared with traditional speaker solutions, it completely eliminates the manual or semi-automatic welding process, greatly improving production efficiency and providing the advantages of large-scale production with better quality assurance. At the same time, AAC can provide an integrated module solution of MEMS speaker + MEMS FB MIC for TWS product manufacturers, fully utilizing of the front cavity space of TWS earphones, making stacking much easier and improving the assembly yield.
Miniaturization, low power consumption and high performance to offer a new technology experience of MEMS
The successful release of SOPRANO, an ultra-small MEMS speaker tweeter unit, further enriches the SSE BU product matrix and will powerfully boost the development of AAC’s smart wearables business.
According to Mr. Shi Tieyong, Vice President for Marketing of AAC’s SSE BU, in recent years, wearable application scenarios entail higher standards for experience in terms of call noise reduction, battery life and wearing comfort, which in turn requires higher product performance. AAC MEMS speakers feature small size, light weight, outstanding sound quality, low power consumption and high reliability, which effectively helps TWS product manufacturers solve the problem of playing Hi-Res sound up until the last mile.
With the continuous progress of technology, MEMS speaker technology will bring higher performance in the future and be applied in a wider range of application scenarios. MEMS speaker technology will bring users a better audio experience and open up a brand-new listening world in TWS, AR/VR, automotive audio and other entertainment and leisure scenarios as well as hearing aids and other professional devices in medical and health fields.