Floating Raised Frame BAW Multiplexer for Spurious Mode Suppression
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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
1Stability of the object's composition
If a raised frame structure is used in BAW devices, then mechanical support and structural stability are improved, but spurious resonances are excited that increase reflection coefficient and reduce Q factor
Solution Approach 1:
The raised frame structure is segmented into discrete posts rather than a continuous frame. This segmentation breaks the continuous structure that excites spurious resonances, while still providing mechanical support through the distributed posts. The posts are spaced apart and electrically isolated, preventing the formation of resonant modes while maintaining structural integrity.
Solution Approach 2:
The harmful continuous frame structure is extracted and replaced with discrete posts. By removing the continuous material that causes spurious resonances and keeping only the essential support function through spaced posts, the invention eliminates the source of the problem while preserving the beneficial mechanical support.
2Strength
If a continuous raised frame is used to support the electrode, then structural support is improved, but spurious modes are excited that increase Gamma loss
Solution Approach 1:
The continuous raised frame is segmented into discrete posts that provide localized support. This segmentation removes the continuous structure that acts as an acoustic waveguide for spurious modes, reducing Gamma loss while maintaining necessary mechanical support through the distributed post array.
Solution Approach 2:
Instead of a uniform continuous frame, localized posts are placed only where mechanical support is needed. The posts have different properties (spaced, electrically isolated) from a continuous frame, providing local support without the global resonant behavior that causes energy loss.
3Stability of the object's composition
If the raised frame is electrically connected to the electrode, then structural stability is improved, but the frame acts as an acoustic waveguide that increases reflection coefficient
Solution Approach 1:
The electrical connection between the raised frame and electrode is extracted/removed. By making the posts electrically isolated through gaps or insulating materials, the invention eliminates the continuous electrical path that enables acoustic waveguiding, thereby reducing reflection coefficient while maintaining structural support function.
Solution Approach 2:
An intermediary (gap or insulating material) is introduced between the posts and the electrode. This intermediary breaks the electrical connection and acoustic coupling, preventing the posts from acting as waveguides while still allowing mechanical support through the physical presence of the posts.
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
a floating raised frame structure positioned on the first side of the piezoelectric layer and spaced apart from the first electrode. The floating raised frame structure is at a floating potential.
Implementation Method 2
a first electrode, a second electrode, a piezoelectric layer positioned between the first electrode and the second electrode... The bulk acoustic wave device is configured to generate a bulk acoustic wave.
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.