Monocrystal SAW Resonator Layout for Higher Frequency Bandwidth
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Solution Overview
Problem
Existing surface acoustic wave (SAW) and bulk acoustic wave (BAW) resonant devices struggle to meet the requirements of modern communication standards for higher frequencies and wider bandwidths while maintaining low manufacturing costs and performance.
Innovation Solution
A resonant device comprising a wafer substrate, a piezoelectric layer made of monocrystal material with specific crystal axis orientations, and an interdigital electrode layer, which generates an electric field perpendicular to the substrate, enhancing wave speed and piezoelectric effect without altering electrode pitch or width, thus improving working frequency and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the working frequency of SAW resonant device is increased by adjusting electrode width, then the working frequency is improved, but the manufacturing cost increases or performance becomes insufficient
Solution Approach 1:
The patent changes the crystal orientation parameters of the piezoelectric substrate from conventional angles to specific angle ranges (e.g., Y-cut lithium niobate with 40°≤θ≤60° from Y-axis, or 30°≤φ≤60° from X-axis). This parameter change in crystal orientation enables higher working frequencies while maintaining reasonable electrode dimensions and manufacturing costs, resolving the contradiction between frequency improvement and cost control.
2Speed
If the working frequency of SAW resonant device is increased by adjusting electrode width, then the working frequency is improved, but the performance becomes insufficient
Solution Approach 1:
By optimizing crystal orientation parameters within specific ranges, the patent improves electromechanical coupling coefficient and wave propagation characteristics. This enables the device to achieve higher working frequencies while maintaining or improving performance metrics such as insertion loss, bandwidth, and temperature stability, thus resolving the contradiction between frequency and performance.
3Speed
If BAW resonant device is used to achieve high frequency and good performance, then the working frequency and performance are improved, but the manufacturing process becomes complex and manufacturing cost increases
Solution Approach 1:
The patent employs a simplified SAW device structure with single-layer or multi-layer piezoelectric films on conventional substrates, avoiding the complex bulk acoustic wave device architecture. By using thin-film deposition techniques and standard semiconductor manufacturing processes, the patent achieves high-frequency performance with simpler fabrication steps, resolving the contradiction between performance improvement and manufacturing complexity.
4Adaptability or versatility
If modern communication standards require higher frequency and wider bandwidth, then the communication capability is improved, but the existing SAW and BAW resonant devices cannot satisfy these requirements
Solution Approach 1:
The patent optimizes crystal orientation parameters within specific ranges to achieve higher working frequencies and wider bandwidths that align with 5G and future communication standards. By adjusting θ or φ angles within the specified ranges, the device can be tuned to meet different frequency requirements while maintaining good electromechanical coupling and temperature stability, thus improving adaptability to modern communication standards.
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
The solution increases the working frequency and performance of the resonant device, aligning with 5G communication standards, while ensuring low manufacturing costs by optimizing the arrangement of crystal axes and electrode layers.
Implementation Method 1
The piezoelectric layer is located on a side of the wafer substrate and includes a piezoelectric monocrystal material
Implementation Method 2
a direction of an electric field generated by the interdigital electrode layer in the piezoelectric layer is a device direction
Data Source
AI summary
Disclosed are a resonant device and an acoustic filter. The resonant device includes a wafer substrate, a piezoelectric layer and an interdigital electrode layer. The piezoelectric layer is located on a side of the wafer substrate and includes a piezoelectric monocrystal material, and the piezoelectric monocrystal material includes a first crystal axis, a second crystal axis and a third crystal axis perpendicular to each other. A direction of an electric field generated by the interdigital electrode layer in the piezoelectric layer is a device direction.