Acoustic Wave Resonator Thickness Variation for Miniaturized Frequency Tuning

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Solution Overview

Problem

Existing acoustic wave devices using piezoelectric layers face challenges in miniaturization, as reducing the number of electrode fingers lowers the Q value and makes it difficult to adjust the resonant frequency.

Innovation Solution

The acoustic wave device incorporates a bulk wave of a thickness slip first-order mode, utilizing a piezoelectric layer with first and second electrodes facing each other. The device includes first and second resonators with different thicknesses, excluding the electrode thickness, allowing for adjustment of the resonant frequency even when miniaturized.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the number of electrode fingers is reduced to miniaturize the device, then the device size is reduced, but the Q value is lowered

Engineering Contradiction:

Improvedevice sizeVSAvoidQ value

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent changes the resonator thickness parameter to adjust the resonant frequency and maintain Q value. By providing first and second resonators with different thicknesses (excluding electrode thickness), the device can achieve different resonant frequencies while maintaining high Q values even with reduced electrode finger counts for miniaturization.

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If the number of electrode fingers is reduced to miniaturize the device, then the device size is reduced, but it becomes difficult to adjust the resonant frequency

Engineering Contradiction:

Improvedevice sizeVSAvoidresonant frequency adjustability

Core Design Contradiction:

Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent uses resonator thickness as a可调 parameter to control resonant frequency. By varying the thickness of different resonators (while excluding electrode thickness from the measurement), the device achieves frequency tuning capability without increasing the number of electrode fingers, thus maintaining miniaturization while enabling frequency adjustment.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent divides the resonator structure into multiple segments with different thicknesses (first resonator and second resonator). This segmentation allows independent control of each resonator's thickness to achieve different resonant frequencies, providing frequency adjustability in a miniaturized device configuration.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If different resonator thicknesses are used to adjust resonant frequency, then resonant frequency adjustability is improved, but device complexity increases

Engineering Contradiction:

Improveresonant frequency adjustabilityVSAvoidresonator structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by making different regions (resonators) have different thicknesses while maintaining the same electrode structure. This allows frequency adjustment through localized thickness variation rather than changing the overall device architecture, thus improving frequency adaptability without proportionally increasing device complexity.

Inventive Principle:

Principle #3Local quality

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 enables an increase in the Q value and allows for adjustable resonant frequencies, even when the device is miniaturized, by effectively utilizing a bulk wave mode and varying the thickness of the resonators.

Implementation Method 1

Acoustic wave devices using plate waves propagating through piezoelectric layers made of LiNbO3 or LiTaO3 have been known

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

The acoustic wave device utilizes a bulk wave of a thickness slip first-order mode

Methodology Applied

Scientific EffectAcoustic wave propagation: Sound

Data Source

PatentUS12324355B2Acoustic wave device

Publication Date: 2025.06.03 MURATA MFG CO LTD

AI summary

An acoustic wave device includes a piezoelectric layer and first and second electrodes facing each other in a direction crossing a thickness direction of the piezoelectric layer. The acoustic wave device utilizes a bulk wave of a thickness slip first-order mode. The acoustic wave device includes first and second resonators. Each of the first and second resonators includes the first and second electrodes, and a setting portion including a setup region where the first and second electrodes are provided in the piezoelectric layer. The thickness of each of the first and second resonators excludes the thickness of the first and second electrodes included in the resonator. The thickness of the first resonator is different from the thickness of the second resonator.