The article titled XBAR Filter Technologies for Wi-Fi Applications discusses the development and application of XBAR (Laterally Excited Shear Mode Bulk Acoustic Wave Resonators) in Wi-Fi filters. Key points from the paper are as follows:
Introduction to XBARs: XBARs are a new type of acoustic wave resonator that were first introduced in 2019. They have garnered attention due to their unique characteristics, such as high frequency and large electromechanical coupling factors, which are difficult to achieve with conventional Surface Acoustic Wave (SAW) and Bulk Acoustic Wave (BAW) devices.
Advantages for Wi-Fi Applications: XBARs are particularly relevant for high-frequency applications like Wi-Fi 6E and Wi-Fi 7 (IEEE 802.11be), which require filters capable of handling frequencies between 5 GHz and 7 GHz. These filters are essential for the increasing bandwidth demands of modern Wi-Fi standards.
Comparison to Other Acoustic Wave Devices: The paper compares XBARs to other acoustic wave devices used in wireless communication, such as FBAR (Film Bulk Acoustic Resonators) and SAW filters. XBARs have distinct advantages, such as requiring no top and bottom electrodes (unlike FBARs), and they operate based on the thickness of the piezoelectric layer, not the electrode thickness, making them easier to handle at high frequencies.
Challenges and Spurious Modes: While XBARs show promise, challenges remain, especially concerning unwanted spurious modes caused by the periodicity of the IDTs (Interdigital Transducers). Methods to suppress these modes through optimization of electrode designs have been proposed and show positive results.
Reliability and Durability: The paper discusses the reliability of XBAR filters, which had previously been unclear due to the fragile nature of their suspended membrane structures. However, the results from various mechanical and environmental stress tests indicate that XBAR filters can meet the reliability standards required for mass production, with performance matching that of traditional SAW and BAW filters.
Wi-Fi Filter Design: The paper outlines the design of Wi-Fi filters using XBAR technology, focusing on filter specifications for Wi-Fi 6E/7, covering frequency bands between 5 to 7 GHz. The paper presents examples of XBAR filters that meet the necessary requirements for low insertion loss and high attenuation.
Conclusion: In conclusion, XBAR filters show significant promise for Wi-Fi applications, offering a wide bandwidth, high coupling factor, and manufacturability. Further advancements in acoustic wave technologies are expected to improve their performance and broaden their application scope.
The paper provides a thorough examination of the XBAR technology, highlighting its potential for high-frequency wireless communication systems like Wi-Fi, alongside the challenges and solutions related to spurious modes and reliability testing .
OMeda (Shanghai Omedasemi Co.,Ltd) was founded in 2021 by 3 doctors with more than 10 years of experience in nanpfabrication. It currently has 15 employees and has rich experience in nanofabrication (coating, lithography, etching, two-photon printing, bonding) and other processes. We support nanofabrication of 4/6/8-inch wafers.