Acoustic Wave Resonator Reflector Layout for Lower Pass Band Loss
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Solution Overview
Problem
Existing acoustic wave duplexers in communication devices face challenges in improving the characteristics of pass bands for both transmission and reception bands, which affects signal filtering efficiency.
Innovation Solution
An acoustic wave element with a piezoelectric substrate and interdigital transducers, featuring a configuration of electrode fingers and reflectors where the reflectors are arranged closer to the excitation electrode, reducing the gap between them, and the pitch of reflection electrode fingers is adjusted to enhance signal propagation and reduce resonator loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gap between the excitation electrode and reflector is reduced, then the pass band characteristics are improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent changes the geometric parameters of the reflector by introducing a shift part that displaces reflection electrode fingers from their regular positions. This parameter modification allows the reflector to maintain effective acoustic reflection while accommodating manufacturing variations in the gap between the excitation electrode and reflector, thereby improving pass band characteristics without proportionally increasing manufacturing precision requirements
Solution Approach 2:
The shift part is introduced locally in the reflector structure rather than uniformly across the entire device. By concentrating the structural modification in the reflection electrode finger positions, the patent achieves improved acoustic performance while limiting the impact on overall manufacturing complexity and precision requirements
2Loss of energy
If the pitch of reflection electrode fingers is adjusted, then the resonator loss is reduced, but the device complexity increases
Solution Approach 1:
The patent modifies the pitch parameter of the reflection electrode fingers in the shift part, changing it from the regular pitch to a different value. This parameter change optimizes the acoustic reflection characteristics and reduces resonator loss. The modification is localized to the shift part, which limits the increase in device complexity compared to a complete redesign of the electrode configuration
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 pass band characteristics by reducing resonator loss and energy leakage, leading to better signal filtering and separation in communication devices.
Implementation Method 1
The acoustic wave element utilizes the feature that an electrical signal and a surface acoustic wave can be converted with each other due to the relationship between the excitation electrode and the piezoelectric substrate
Implementation Method 2
two reflectors arranged on the piezoelectric substrate, each of which includes a plurality of reflection electrode fingers, which sandwich the excitation electrode in the propagation direction of the acoustic wave
Data Source
AI summary
An acoustic wave element of the present invention includes a piezoelectric substrate, an excitation electrode which is arranged on the piezoelectric substrate and includes a plurality of electrode fingers, and two reflectors arranged on the piezoelectric substrate, each of which includes a plurality of reflection electrode fingers, which sandwich the excitation electrode therebetween in the propagation direction of an acoustic wave. The excitation electrode includes a main region in the center vicinity of the line of the plurality of electrode fingers in which the intervals between the centers of the plurality of electrode fingers are uniformly a first interval. In the reflector, at least one of the reflection electrode fingers shifts to the excitation electrode side relative to virtual electrode finger positions which are repeatedly set at the first intervals from the electrode fingers in the main region.