LiNbO3 Elastic Wave Resonator Tuning With Suppressed SH Spurious Modes
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Solution Overview
Problem
Existing elastic wave devices experience significant changes in spurious SH (Shear Horizontal) wave responses when the thickness of the frequency adjustment film is altered, leading to instability in frequency adjustment.
Innovation Solution
The elastic wave device incorporates a LiNbO3 substrate with an interdigital transducer electrode, a dielectric film, and a frequency adjustment film, where the Euler Angles of the LiNbO3 substrate and the film thickness of the main electrode are optimized to satisfy a specific formula, reducing the spurious SH wave response even when the frequency adjustment film thickness is changed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the thickness of the frequency adjustment film is changed to adjust the frequency, then the frequency adjustment sensitivity is improved, but the spurious SH wave response changes significantly
Solution Approach 1:
The patent applies parameter changes by optimizing the Euler Angles (θ) of the LiNbO3 substrate and the film thickness of the main electrode to satisfy a specific formula relationship. This parameter optimization ensures that when the frequency adjustment film thickness is changed for frequency tuning, the spurious SH wave response remains suppressed, resolving the contradiction between frequency adjustment sensitivity and response stability.
2Measurement precision
If the film thickness of the frequency adjustment film is reduced to increase adjustment sensitivity, then the frequency adjustment sensitivity is improved, but the spurious SH wave response becomes more significant
Solution Approach 1:
The patent applies preliminary anti-action by pre-optimizing the Euler Angles (θ) of the LiNbO3 substrate and the main electrode thickness before applying the frequency adjustment film. This preliminary configuration creates a baseline that suppresses spurious SH wave responses, allowing the frequency adjustment film thickness to be reduced for high sensitivity without triggering harmful SH wave responses.
3Reliability
If the Euler Angles and electrode thickness are optimized to suppress spurious SH wave response, then the spurious SH wave response is reduced, but the frequency adjustment sensitivity may be compromised
Solution Approach 1:
The patent resolves this contradiction through parameter changes by establishing a specific formula relationship between the Euler Angles (θ) of the LiNbO3 substrate and the main electrode thickness. This optimized parameter combination simultaneously achieves spurious SH wave response suppression and maintains high frequency adjustment sensitivity, allowing the frequency adjustment film thickness to be minimized for high sensitivity.
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 effectively minimizes changes in spurious SH wave responses and maintains high frequency adjustment sensitivity, reducing production costs and ensuring stable device characteristics.
Implementation Method 1
an interdigital transducer electrode disposed on the LiNbO3 substrate
Data Source
AI summary
An elastic wave device includes an interdigital transducer electrode, a dielectric film, and a frequency adjustment film are disposed on a LiNbO3 substrate. When Euler Angles of the LiNbO3 substrate are within a range of about 0°±5°, within a range of about θ±1.5°, within a range of about 0°±10°, the interdigital transducer electrode includes a main electrode, a film thickness of the main electrode normalized by a wavelength determined in accordance with an electrode finger pitch of the interdigital transducer electrode is denoted as T, and a density ratio of a material of the main electrode to Pt is denoted as r, the film thickness of the main electrode and θ of the Euler Angles satisfy θ=−0.05°/(T/r−0.04)+31.35°.