6.5 GHz Wi-Fi Front-End Module With Single-Crystal BAW Filter
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Solution Overview
Problem
Conventional bulk acoustic wave resonators using polycrystalline piezoelectric thin films face degradation at frequencies above 5 GHz due to poor crystalline quality, limiting their performance in high-frequency applications, while single crystalline films maintain quality but are challenging to manufacture and transfer effectively.
Innovation Solution
The development of a method and structure for bulk acoustic wave resonator devices using single crystal piezoelectric thin films, integrated into a front-end module with a power amplifier, diversity switch, and low noise amplifier, which includes a 6.5 GHz resonator and a single pole two throw switch, enabling efficient high-frequency operation with a compact form factor and reduced size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If polycrystalline piezoelectric thin films are used in bulk acoustic wave resonators, then manufacturing is easier and cost is lower, but crystalline quality degrades at frequencies above 5 GHz
Solution Approach 1:
The patent changes the fundamental material parameter from polycrystalline to single-crystal piezoelectric thin films. This parameter change maintains manufacturing feasibility through established single-crystal growth techniques while dramatically improving crystalline quality and electro-mechanical coupling coefficients, enabling reliable operation at frequencies above 5 GHz where polycrystalline films degrade.
2Reliability
If single crystal piezoelectric thin films are used to maintain crystalline quality at high frequencies, then performance improves, but manufacturing and transfer become challenging
Solution Approach 1:
The patent segments the manufacturing process into distinct stages: single-crystal film growth on a substrate, patternning of electrodes and interconnects, and controlled transfer to the final device. This segmentation allows each stage to be optimized independently, making single-crystal fabrication more manageable while preserving crystalline quality throughout the process.
Solution Approach 2:
The patent uses a substrate as an intermediary during the single-crystal growth process. The substrate provides a controlled environment for growing high-quality single-crystal piezoelectric films, which can then be transferred to the final device structure. This intermediary approach simplifies the overall manufacturing process while maintaining crystalline quality.
3Adaptability or versatility
If conventional RF technology is used, then current limitations are acceptable, but future high-frequency performance will be problematic
Solution Approach 1:
The patent changes key material parameters including piezoelectric coupling coefficients and acoustic velocity by transitioning to single-crystal films. These parameter changes enable the resonators to operate reliably at higher frequencies (6.5 GHz and above), providing adaptability for future wireless communication standards while maintaining current performance requirements.
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 solution provides high-performance RF filters with improved quality factor and electro-mechanical coupling, enabling efficient operation at frequencies up to 6.5 GHz, while maintaining a compact form factor and reducing overall size, thus addressing the limitations of conventional technologies.
Implementation Method 1
bulk acoustic wave resonator devices using single crystal piezoelectric thin films
Data Source
AI summary
A front end module (FEM) for a 6.5 GHz Wi-Fi acoustic wave resonator RF filter circuit. The device can include a power amplifier (PA), a 6.5 GHz resonator, and a diversity switch. The device can further include a low noise amplifier (LNA). The PA is electrically coupled to an input node and can be configured to a DC power detector or an RF power detector. The resonator can be configured between the PA and the diversity switch, or between the diversity switch and an antenna. The LNA may be configured to the diversity switch or be electrically isolated from the switch. Another 6.5 GHZ resonator may be configured between the diversity switch and the LNA. In a specific example, this device integrates a 6.5 GHz PA, a 6.5 GHZ bulk acoustic wave (BAW) RF filter, a single pole two throw (SP2T) switch, and a bypassable LNA into a single device.