IDT Resonator Electrode Layout for Transverse-Mode Spurious Suppression
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Solution Overview
Problem
Existing acoustic wave devices are unable to sufficiently suppress transverse-mode spurious, which affects the device's performance and reliability.
Innovation Solution
The acoustic wave device incorporates a piezoelectric substrate, a support substrate, and a multimode resonator with IDT electrodes that include busbars, electrode fingers, and dummy electrodes. The dummy electrodes have lengths that continuously change from one end portion to the other end portion of the busbar, and the electrode fingers have wide-width regions to effectively suppress transverse-mode spurious.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If wide-width regions are provided in the electrode finger, then transverse-mode spurious is suppressed to some extent, but transverse-mode spurious cannot be sufficiently suppressed
Solution Approach 1:
The electrode structure is segmented into multiple functional zones: standard-width electrode fingers for main-mode operation, wide-width regions for spurious suppression, and dummy electrodes with continuously changing lengths. This segmentation allows each zone to perform its specific function optimally, achieving sufficient transverse-mode spurious suppression while maintaining device performance.
Solution Approach 2:
Different regions of the electrode structure are given different local qualities: the electrode fingers have standard width for efficient main-mode wave generation, while specific wide-width regions are positioned at locations where transverse-mode waves are generated, and dummy electrodes with continuously varying lengths are added to create localized acoustic impedance variations. This local quality differentiation enables targeted suppression of transverse-mode spurious without affecting overall device performance.
2Object-affected harmful factors
If dummy electrodes with continuously changing lengths are added, then transverse-mode spurious is effectively suppressed, but device complexity increases
Solution Approach 1:
The dummy electrodes are merged with the existing IDT electrode structure, sharing the same busbar connections and substrate integration. The dummy electrodes with continuously changing lengths are positioned adjacent to the standard electrode fingers, forming an integrated structure that suppresses transverse-mode spurious while maintaining a compact and relatively simple overall device architecture.
Solution Approach 2:
The dummy electrodes are designed with continuously changing lengths from one end to the other, creating a gradual parameter variation that generates acoustic impedance gradients. This parameter change approach effectively suppresses transverse-mode spurious by disrupting the resonance conditions for unwanted modes, while the continuous variation can be implemented through standard photolithography processes, avoiding excessive manufacturing complexity.
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 significantly suppresses transverse-mode spurious within the passband, enhancing the device's performance and reliability by reducing unwanted frequency components.
Implementation Method 1
a piezoelectric substrate, a support substrate bonded to the piezoelectric substrate, and a multimode resonator comprising a plurality of pairs of IDT electrodes arranged side by side and formed on the other side of the support substrate on the piezoelectric substrate that generates a main-mode wave and a transverse-mode wave when power is applied
Data Source
AI summary
An acoustic wave device includes a piezoelectric substrate, a support substrate bonded to the piezoelectric substrate, and a resonator comprising a plurality of pairs of IDT electrodes arranged side by side that generates main-mode wave and transverse-mode wave when power is applied. The resonator includes a first busbar, a second busbar opposed to the first busbar, a plurality of first electrode fingers connected to a side of the second busbar in the first busbar, a plurality of second electrode fingers connected to a side of the first busbar in the second busbar, a plurality of first dummy electrodes connected to the side of the second busbar in the first busbar and opposed to the plurality of second electrode fingers, and a plurality of second dummy electrodes connected to the side of the first busbar in the second busbar and opposed to the plurality of first electrode fingers.