Elastic Wave Filter Structure for Suppressing Parasitic Acoustic Modes
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Solution Overview
Problem
Conventional electrode structures in electro-acoustic resonators excite parasitic acoustic modes, degrading the performance of filters.
Innovation Solution
The elastic wave device incorporates specific Euler angles for the substrate and piezoelectric layer, optionally with intermediate layers of varying acoustic velocities, to suppress parasitic acoustic modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electrode structure is used in an electro-acoustic resonator, then the device can convert between electromagnetic signals and acoustic RF signals, but parasitic acoustic modes are excited that degrade filter performance
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Euler angles of the substrate and piezoelectric layer. The substrate Euler angles are set to (0°±10°, ±90°±10°, ±45°±10°) and the piezoelectric layer Euler angles to specific combinations such as (0°±10°, 120°±5°, 0°±10°), (0°±10°, 130°±5°, 0°±10°), or (0°±10°, 140°±5°, 0°±10°). This precise angular parameter control suppresses parasitic acoustic modes while maintaining the desired acoustic mode generation, thereby improving filter performance without sacrificing the electro-acoustic conversion function
Solution Approach 2:
The patent employs composite material structures by combining specific substrate materials (such as silicon) with piezoelectric layers (including LiTaO3, LiNbO3, ZnO, AlN, or PZT) oriented at specific Euler angles. This composite structure with controlled crystal orientations suppresses parasitic acoustic modes while maintaining effective electro-acoustic conversion, resolving the contradiction between functionality and parasitic suppression
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
Effectively suppresses high-frequency spurious waves by 15 dB within 3.5-5 GHz, enhancing electrical performance.
Implementation Method 1
In an electro-acoustic resonator, due to the piezoelectric effect, an electrode structure combined with a piezoelectric material converts between electromagnetic signals and acoustic RF signals.
Implementation Method 2
Euler angles of the substrate are (0°±10°, ±90°±10°, ±45°±10°); and Euler angles of the piezoelectric layer are (0°±10°, 120°±5°, 0°±10°), or (0°±10°, 130°±5°, 0°±10°), or (0°±10°, 140°±5°, 0°±10°)
Data Source
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Figure 3A~3B
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AI summary
The present application discloses an elastic wave device, a filter, and a multiplexer, which relate to the field of integrated circuit technologies. The elastic wave device includes: a substrate, a piezoelectric layer arranged on the substrate, and an IDT electrode formed on the piezoelectric layer. Euler angles of the substrate are (0°±10°, ±90°±10°, ±45°±10°). Euler angles of the piezoelectric layer are (0°±10°, 120°±5°, 0'±10') or (0°±10°, 130°±5°, 0°±10°), or (0°±10°, 140°±5°, 0°±10°). This configuration addresses the problem that parasitic acoustic modes generated in the conventional technologies affect an electrical performance of a device, thereby achieving the effect of suppressing parasitic acoustic modes and improving electrical performance through a combination of the Euler angles of the substrate and the piezoelectric layer.