Floating Raised Frame BAW Multiplexer for Low Gamma Loss
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Solution Overview
Problem
Bulk acoustic wave devices face challenges in achieving high quality factor (Q) and low Gamma loss, with raised frames often exciting spurious resonances that increase reflection coefficient, particularly in carrier aggregation applications.
Innovation Solution
Incorporating a floating raised frame structure with a gap between the perimeter and active region, which is electrically isolated from the electrode, to suppress spurious modes and maintain high Q without degrading electromechanical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a raised frame structure is used in BAW devices, then structural support and electrode positioning are improved, but spurious resonances are excited that increase reflection coefficient
Solution Approach 1:
The patent extracts the harmful function of the raised frame by electrically isolating it from the electrode using an insulating layer. This allows the raised frame to maintain its structural support function while removing its ability to generate spurious resonances through electrical coupling with the piezoelectric layer.
Solution Approach 2:
An insulating layer is introduced as an intermediary between the raised frame and the electrode. This intermediary prevents direct electrical coupling, thereby blocking the transmission of spurious resonances from the raised frame to the active piezoelectric structure while maintaining mechanical support.
2Reliability
If electrode thickness is increased in overlap region, then electromechanical coupling is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The electrode is designed with local quality variation, featuring a thicker overlap region only where needed for enhanced electromechanical coupling, while other regions maintain standard thickness. This localized thickening optimizes performance without unnecessarily increasing overall device complexity.
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 floating raised frame structure reduces and eliminates spurious modes, achieving high Q and low Gamma loss, enhancing multiplexer performance by minimizing reflection coefficient in carrier aggregation bands.
Implementation Method 1
In BAW resonators, acoustic waves propagate in a bulk of a piezoelectric layer
Data Source
AI summary
Aspects of this disclosure relate to a bulk acoustic wave device with a floating raised frame structure. The bulk acoustic wave device includes a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode, and a floating raised frame structure positioned on a same side of the piezoelectric layer as the first electrode and spaced apart from the first electrode. The floating raised frame structure is at a floating potential. The bulk acoustic wave device can suppress a raised frame mode. Related methods, filters, multiplexers, radio frequency front ends, radio frequency modules, and wireless communication devices are disclosed.