The Generation-V mobile communication technology (5G technology or 5G for short) is the latest generation of cellular mobile communication technology and it is also an extension of 4G (LTE-A and WiMax), 3G (UMTS and LTE) and 2G (GSM) systems. The performance goal of 5G is to have a high data rate, reduce delay, save energy, reduce cost, and improve system capacity and large-scale equipment connection.
Among known piezoelectric materials, the AlN thin film has the fastest SAW propagation speed, the AlN SAW device has good chemical and thermal stability and extremely high sensitivity to the external environment including pressure, temperature, stress, and gas, and is compatible with conventional Si CMOS technology, thus becoming a key component for passive sensing, wireless sensing, and mobile signal processing. With the rapid development of wireless communication technology in the recent ten years, SAW sensors, resonators, and filters are expected to replace traditional semiconductor devices in realizing miniaturization, multifunction and high-cost performance, and become the core technology of future complex systems.
The filter mainly includes Film Bulk Acoustic Resonator (FBAR) filter, Surface Acoustic Wave (SAW) filter, and Bulk Acoustic Wave (BAW) filter. FBAR is widely used in future single-chip multi-band wireless communication RF front-end systems and has more advantages in size than SAW filter; the application of AlN in SAW/BAW filters is relatively mature and commercialization has been realized. SAW Filter is mostly used in intermediate frequency, and BAW Filter is more suitable for high-frequency applications, and the high-quality factor Q value is higher. It will be widely used in 4G/5G and other communication fields.