Stacked BAW Filter Circuit for Narrower Transition Bands
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Solution Overview
Problem
Existing electronic filter circuits suffer from disadvantages such as wide transition bands and lower rejection performance, which affect their efficiency in filtering radio frequency signals.
Innovation Solution
The integration of an integrated passive device and a bulk acoustic wave filter, where the integrated passive device serves as a cover for the bulk acoustic wave filter, with conductive pillars connecting electrodes, forming a cavity protected by a peripheral wall, enhances the combination of narrow transition bands and improved rejection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing electronic filter circuits are used, then the device structure is simple, but the transition bands are wide and rejection performance is low
Solution Approach 1:
The patent combines an integrated passive device (IPD) filter and a bulk acoustic wave (BAW) filter into a single stacked configuration. The IPD filter provides wideband rejection while the BAW filter delivers narrow transition bands, achieving both wide rejection bandwidth and sharp selectivity that neither filter could provide alone.
Solution Approach 2:
The patent transitions from planar integration to three-dimensional vertical stacking. The IPD filter and BAW filter are stacked vertically and connected through conductive pillars, utilizing the vertical dimension to integrate multiple filter functions in a compact footprint while maintaining individual filter performance characteristics.
2Manufacturing precision
If existing electronic filter circuits are used, then the device occupies less space, but the rejection performance is low
Solution Approach 1:
The stacked configuration merges IPD and BAW filters vertically, allowing the combination of wide rejection bandwidth from IPD and narrow transition bands from BAW without requiring lateral expansion. This vertical integration achieves superior rejection performance while maintaining compact device volume.
Solution Approach 2:
The conductive pillars are embedded within cavities formed in the IPD substrate, with the BAW filter stacked above. This nested arrangement integrates connection structures within the available space, maximizing volume utilization while achieving both compact size and high rejection performance.
3Strength
If the integrated passive device forms a cover for the bulk acoustic wave filter, then mechanical protection is provided and space is saved, but the manufacturing complexity increases
Solution Approach 1:
The IPD substrate serves multiple functions: it acts as the structural base for the IPD filter, provides mechanical protection as a cover for the BAW filter, and serves as the mounting platform for conductive pillars. This multi-functionality reduces the need for separate protective structures while integrating multiple functions into a single component.
Solution Approach 2:
The manufacturing process is segmented into distinct stages: first forming the IPD filter and cavities in the substrate, then stacking the BAW filter, and finally forming conductive pillars to connect the two filters. This segmentation of manufacturing steps simplifies the overall process by breaking down complex integration into manageable sequential operations.
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 filter circuit with narrower transition bands and better rejection performance, while also providing mechanical protection and space savings.
Implementation Method 1
a bulk acoustic wave filter stacked on the integrated passive device
Data Source
AI summary
The present description concerns electronic filter circuit comprising an integrated passive device; a bulk acoustic wave filter stacked on the integrated passive device on the side of a first surface of the integrated passive device; and at least one conductive pillar crossing the integrated passive device and connecting an electrode of the bulk acoustic wave filter to a contacting element located on a second surface of the integrated passive device opposite to the first surface and intended to be connected to an external element.