IDT Electrode End-Part Layout for Lower-Loss Acoustic Resonators
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Solution Overview
Problem
Existing acoustic wave elements in communication devices suffer from high loss, which affects the performance of filters used in mobile terminals and communication apparatuses, necessitating a solution to reduce resonator losses.
Innovation Solution
The acoustic wave element incorporates an IDT electrode with multiple electrode fingers and reflector electrodes, where the IDT electrode is divided into a major part and end parts that are electrically connected in parallel and series, maintaining the same pitch as the major part to minimize acoustic wave leakage and loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the IDT electrode is extended to increase the resonator performance, then the acoustic wave leakage increases and loss increases
Solution Approach 1:
The IDT electrode is segmented into a major part and end parts, where the end parts are positioned between the major part and the reflector electrodes. This segmentation allows the end parts to specifically address acoustic wave leakage at the edges while the major part maintains the primary resonant function, thereby improving resonator performance without proportionally increasing loss.
Solution Approach 2:
The end parts of the IDT electrode are configured with specific characteristics (positioned between the major part and reflector electrodes) to locally address the problem of acoustic wave leakage at the edges. This local optimization allows the majority of the electrode to maintain its original design while specifically targeting the loss mechanism at critical locations.
2Ease of manufacture
If the IDT electrode structure is simplified, then the manufacturing is easier, but the acoustic wave leakage increases and loss increases
Solution Approach 1:
The IDT electrode is divided into a major part and end parts that can be fabricated as a continuous structure or separately and connected. This segmentation allows flexibility in manufacturing approaches while maintaining the functional benefits of having dedicated end parts to reduce acoustic wave leakage.
Solution Approach 2:
The end parts are electrically connected in parallel with the major part, creating a unified electrode structure that functions as a single integrated component. This merging approach simplifies the electrical connections while maintaining the distributed functionality of different regions for reducing acoustic wave loss.
3Reliability
If the end part is electrically connected in parallel with the major part, then the resonator performance improves, but the device complexity increases
Solution Approach 1:
The end parts are electrically connected in parallel with the major part through conductive structures that are integrated into the overall electrode design. This merging approach allows the parallel connection to be achieved without requiring separate external connections, thereby improving resonator performance while minimizing the increase in device complexity.
Solution Approach 2:
The IDT electrode structure serves multiple functions: the major part provides the primary resonant function while the end parts reduce acoustic wave leakage, and the parallel electrical connection integrates both functions into a single component. This multi-functionality reduces the need for additional separate components, offsetting the complexity introduced by the parallel connection.
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 results in a resonator with reduced loss, enhancing communication quality by concentrating acoustic waves at the center of the IDT electrode and suppressing leakage, thereby improving filter performance.
Implementation Method 1
The acoustic wave element utilizes a characteristic of being able to mutually convert an electrical signal and a surface acoustic wave (SAW) in the relationship between the IDT electrode and the piezoelectric substrate
Implementation Method 2
reflector electrodes on the two sides of the IDT electrode
Data Source
AI summary
An acoustic wave element includes an IDT electrode includes pluralities of electrode fingers, and reflector electrodes on the two sides of the IDT electrode. The IDT electrode includes a major part and at least one end part which is located between the major part and one of the reflector electrodes and is arranged along a direction of propagation of an acoustic wave together with the major part. the at least one end part includes a pitch of the plurality of electrode fingers substantially the same as a pitch of the plurality of electrode fingers in the major part, is electrically connected in parallel with respect to the major part, and is divided into two or more sections which are electrically connected in series with each other.