BAW RF Filter Topologies for 5.5 GHz Wi-Fi and 5G Coexistence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current bulk acoustic wave resonators using polycrystalline piezoelectric thin films degrade quickly at thicknesses below 0.5 um, limiting their performance at frequencies above 5 GHz, while single crystalline films maintain quality but are challenging to manufacture and transfer effectively.
Innovation Solution
The development of manufacturing processes and structures for high-quality bulk acoustic wave resonators using single crystalline or epitaxial piezoelectric thin films, including transfer processes that provide a flat, high-quality, single-crystal piezoelectric film for superior acoustic wave control and high Q factors, overcoming the limitations of polycrystalline layers and complex electrode structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polycrystalline piezoelectric thin films are used in bulk acoustic wave resonators, then the manufacturing process is simpler and cost is lower, but the quality factor degrades quickly when thickness decreases below 0.5 um, limiting performance at frequencies above 5 GHz
Solution Approach 1:
The patent changes the fundamental material parameter from polycrystalline to single-crystalline structure. This parameter change enables the resonator to maintain high quality factor at thicknesses below 0.5 um, which is critical for achieving frequencies above 5 GHz while preserving manufacturing feasibility through wafer-level integration processes
2Reliability
If single crystalline piezoelectric thin films are used to maintain quality factor at high frequencies, then the quality factor and electro-mechanical coupling are enhanced, but the manufacturing and transfer processes become more complex and challenging
Solution Approach 1:
The patent segments the manufacturing process into distinct stages: growing single-crystalline films on separate wafer substrates, processing them independently to achieve high quality factor, and then integrating them into the final resonator device. This segmentation allows the complex single-crystalline film processing to be performed in controlled environments before integration, reducing overall manufacturing complexity
Solution Approach 2:
The patent uses wafer-level processing as an intermediary approach. Instead of directly transferring individual single-crystalline resonators, the process works at the wafer level, allowing batch processing and integration. This intermediary approach simplifies the manufacturing by maintaining the high quality factor benefits of single-crystalline films while using standardized semiconductor manufacturing techniques
3Speed
If piezoelectric thin film thickness is reduced to increase resonator frequency above 5 GHz, then the operating frequency increases, but polycrystalline films degrade quickly and can no longer maintain adequate quality factor
Solution Approach 1:
The patent changes the material structure parameter from polycrystalline to single-crystalline, which fundamentally alters the thickness-frequency-quality factor relationship. This parameter change enables the resonator to operate at frequencies above 5 GHz with reduced thickness while maintaining high quality factor, overcoming the limitation of polycrystalline films that degrade below 0.5 um thickness
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the production of high-performance RF filters with enhanced quality factor and electro-mechanical coupling, meeting the demands of high-frequency applications such as 5G and Wi-Fi, with improved cost-efficiency and reliability.
Implementation Method 1
bulk acoustic wave resonators using polycrystalline piezoelectric thin films
Implementation Method 2
bulk acoustic wave resonators (BAWR) using crystalline piezoelectric thin films are leading candidates for meeting such demands
Data Source
AI summary
An RF circuit device using modified lattice, lattice, and ladder circuit topologies. The devices can include four resonator devices and four shunt resonator devices. In the ladder topology, the resonator devices are connected in series from an input port to an output port while shunt resonator devices are coupled the nodes between the resonator devices. In the lattice topology, a top and a bottom serial configurations each includes a pair of resonator devices that are coupled to differential input and output ports. A pair of shunt resonators is cross-coupled between each pair of a top serial configuration resonator and a bottom serial configuration resonator. The modified lattice topology adds baluns or inductor devices between top and bottom nodes of the top and bottom serial configurations of the lattice configuration. These topologies may be applied using single crystal or polycrystalline bulk acoustic wave (BAW) resonators.