Lamb Wave Resonator Engineered Border Region for Transverse Mode Suppression
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Solution Overview
Problem
Existing acoustic wave resonators face challenges in achieving high quality factor (Q) and suppressing transverse modes, particularly in Lamb wave resonators with piston mode structures.
Innovation Solution
The Lamb wave resonator incorporates a piezoelectric layer with an engineered region having a lower effective piezoelectric coefficient than the active region, combined with a piston mode structure and specific electrode designs, such as hammer head shapes, to suppress transverse modes and enhance quality factor (Q).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a piston mode structure is used in Lamb wave resonators, then transverse modes can be suppressed, but the quality factor (Q) is reduced
Solution Approach 1:
The piezoelectric layer is engineered to have different effective piezoelectric coefficients in different regions: a lower coefficient in the border region and a higher coefficient in the active region. This spatial variation in material properties allows the border region to suppress transverse modes while the active region maintains high quality factor performance.
2Ease of manufacture
If the piezoelectric layer has uniform properties, then manufacturing is simplified, but transverse modes cannot be effectively suppressed
Solution Approach 1:
The piezoelectric layer is engineered to have different effective piezoelectric coefficients in different regions: a lower coefficient in the border region and a higher coefficient in the active region. This spatial variation in material properties allows the border region to suppress transverse modes while the active region maintains high quality factor performance.
Solution Approach 2:
The effective piezoelectric coefficient is deliberately varied across the piezoelectric layer by engineering the border region to have a lower coefficient than the active region. This parameter change enables selective suppression of transverse modes at the boundaries while preserving strong piezoelectric coupling in the active region for high Q operation.
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
The engineered region and electrode design effectively suppress transverse modes, allowing the resonator to operate in desired symmetric modes with improved electromechanical coupling and reduced spurious signals, enhancing performance and efficiency.
Implementation Method 1
The piezoelectric layer has an effective piezoelectric coefficient in the border region with a lower magnitude than an effective piezoelectric coefficient in the active region
Data Source
AI summary
Aspects of this disclosure relate to a Lamb wave resonator with a piezoelectric layer that is less piezoelectric in a border region than in an active region. End portions of interdigital transducer electrode fingers of the Lamb wave resonator are in the border region. Related filters, multiplexers, radio frequency modules, radio frequency systems, wireless communication devices, and methods are also disclosed.