Angled Comb-Electrode Acoustic Resonator for Spurious Response Control
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Solution Overview
Problem
Conventional acoustic wave resonators suffer from spurious responses due to transverse modes, which deteriorate their Q value and performance in high-frequency devices like mobile phones and wireless LAN terminals.
Innovation Solution
The acoustic wave resonator design features a piezoelectric substrate with comb-shaped electrodes that interdigitate at a specific angle, preventing standing waves and suppressing transverse mode waves, and includes a dielectric film to further reduce spurious responses, thereby enhancing the Q value and frequency-temperature characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional comb-shaped electrodes with perpendicular electrode fingers and busbars are used, then the device structure is simple and easy to manufacture, but spurious responses occur due to transverse modes causing deterioration of Q value
Solution Approach 1:
The patent applies asymmetry by configuring the electrode fingers to extend in a direction that is not perpendicular to the busbar direction, creating an asymmetric electrode structure that suppresses transverse modes and spurious responses while maintaining manufacturability
Solution Approach 2:
The patent changes the geometric parameters of the electrode structure, specifically the angle between electrode fingers and busbars, optimizing this parameter to suppress spurious responses and improve Q value without significantly complicating the manufacturing process
2Reliability
If electrode fingers extend perpendicular to busbars, then the electrode structure is symmetric and easy to fabricate, but standing waves and transverse mode waves are generated deteriorating performance
Solution Approach 1:
The patent deliberately introduces asymmetry in the electrode configuration by setting the electrode finger extension direction at a non-perpendicular angle to the busbar, which prevents standing wave formation and suppresses transverse modes while remaining compatible with standard fabrication processes
3Productivity
If conventional perpendicular electrode configuration is used, then manufacturing is straightforward, but spurious responses and Rayleigh waves occur reducing acoustic wave resonator efficiency
Solution Approach 1:
The patent optimizes the geometric parameters of the electrode structure, specifically adjusting the angle between electrode fingers and busbars from the conventional perpendicular configuration to a non-perpendicular angle, which suppresses spurious responses and Rayleigh waves to improve acoustic wave resonator efficiency
Solution Approach 2:
The patent employs asymmetric electrode geometry where electrode fingers are oriented at a non-perpendicular angle to busbars, creating an asymmetric structure that eliminates spurious responses and enhances productivity without requiring complex manufacturing processes
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 design effectively suppresses spurious responses caused by transverse modes, leading to a higher Q value and improved performance in high-frequency devices by preventing standing waves and Rayleigh waves, thus enhancing the acoustic wave resonator's efficiency and stability.
Implementation Method 1
piezoelectric substrate
Implementation Method 2
first and second comb-shaped electrodes provided on the piezoelectric substrate
Implementation Method 3
acoustic wave resonator
Data Source
AI summary
An acoustic wave resonator includes a piezoelectric substrate and first and second comb-shaped electrodes provided on the piezoelectric substrate and interdigitating with each other. The first comb-shaped electrode includes a first busbar and first electrode fingers extending in a direction non-perpendicular to a direction in which the first busbar extends. The second comb-shaped electrode includes a second busbar and second electrode fingers extending from the second busbar and interdigitating with the first electrode fingers at an interdigitating region. This acoustic wave resonator can suppress a spurious response due to a transverse mode and has a high Q value.