Quartz-LiTaO3 SAW Resonator Electrode Tuning for Spurious Response
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Solution Overview
Problem
Current surface acoustic wave (SAW) devices face challenges in achieving optimal resonance and filtering performance due to limitations in the thickness and mass density of interdigital transducer electrodes, which affect the wavelength and metallization ratio, leading to issues with impedance ratio and spurious responses.
Innovation Solution
The proposed surface acoustic wave device incorporates a quartz substrate with a piezoelectric plate made from LiTaO3 or LiNbO3, featuring a thickness greater than 2λ and an interdigital transducer electrode with a mass density in specific ranges, along with a metallization ratio and thickness calculations to optimize electrode design, enhancing resonance and filtering capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interdigital transducer electrode thickness is increased to improve resonance performance, then the impedance ratio improves, but the device complexity increases due to precise thickness and density requirements
Solution Approach 1:
The patent applies parameter changes by specifying precise electrode thickness ranges (0.036λ to 0.148λ) and mass density values (1.50 g/cm³, 6.00 g/cm³, or 12.0 g/cm³) to optimize the impedance ratio. This quantitative parameter optimization resolves the contradiction by providing specific design guidelines that improve reliability while managing complexity through defined parameters.
Solution Approach 2:
The patent employs partial action by providing multiple discrete mass density options (1.50, 6.00, or 12.0 g/cm³) rather than requiring a continuous range. This allows designers to select appropriate density levels based on specific application requirements, improving impedance ratio while avoiding the complexity of continuous parameter optimization.
2Reliability
If the piezoelectric plate thickness is increased to reduce spurious responses, then filtering performance improves, but the device size increases
Solution Approach 1:
The patent applies parameter changes by specifying the piezoelectric plate thickness should be greater than 2λ (wavelength). This quantitative parameter specification improves filtering performance and reduces spurious responses while providing a clear design criterion that balances performance improvement with size management.
3Measurement precision
If the metallization ratio is optimized to improve resonance characteristics, then the wavelength control improves, but the manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by defining specific metallization ratio ranges and corresponding electrode thickness specifications. These quantified parameters enable wavelength control while providing manufacturable design targets that balance precision requirements with fabrication capabilities.
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 configuration improves the impedance ratio and reduces spurious responses, providing better filtering performance and stability for SAW devices, particularly in radio-frequency applications.
Implementation Method 1
a piezoelectric plate formed from LiTaO3 or LiNbO3 and disposed over the quartz substrate
Implementation Method 2
an interdigital transducer electrode formed over the piezoelectric plate... providing resonance of a surface acoustic wave
Data Source
AI summary
Surface acoustic wave devices and related methods. In some embodiments, a surface acoustic wave device for providing resonance of a surface acoustic wave having a wavelength λ can include a quartz substrate and a piezoelectric plate formed from LiTaO3 or LiNbO3 disposed over the quartz substrate. The piezoelectric plate can have a thickness greater than 2λ. The surface acoustic wave device can further include an interdigital transducer electrode formed over the piezoelectric plate. The interdigital transducer electrode can have a mass density ρ in a range 1.50 g/cm3<ρ≤6.00 g/cm3, 6.00 g/cm3<ρ≤12.0 g/cm3, or 12.0 g/cm3<ρ≤23.0 g/cm3, and a thickness greater than 0.148λ, greater than 0.079λ, or greater than 0.036λ, respectively.