Stacked BAW-on-SAW Filter Layout for Smaller RF Footprints
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Solution Overview
Problem
Current acoustic wave filters face challenges in reducing size while maintaining performance and cost-effectiveness, particularly in radio frequency electronic systems, where achieving desirable filter performance in smaller modules is difficult.
Innovation Solution
The solution involves a stacked arrangement of acoustic wave devices, including bulk acoustic wave (BAW) resonators positioned over surface acoustic wave (SAW) devices, utilizing a temperature compensation layer and conductive vias for interconnection, allowing for a hybrid acoustic wave filter component with reduced size and enhanced design freedom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If acoustic wave filters are made smaller to reduce size, then the footprint is reduced, but filter performance deteriorates
Solution Approach 1:
The patent transitions from planar arrangement to three-dimensional stacked configuration, placing BAW resonators vertically above SAW devices. This vertical stacking enables multiple acoustic wave devices to occupy the same footprint area while maintaining their individual performance characteristics, effectively resolving the contradiction between small size and filter performance
2Area of stationary object
If multiple acoustic wave devices are stacked to reduce footprint, then device integration increases, but manufacturing complexity increases
Solution Approach 1:
The patent divides the acoustic wave filter into functionally independent segments (SAW devices and BAW resonators) that can be designed, manufactured, and tested separately before being stacked together. This segmentation reduces manufacturing complexity by allowing each component to be optimized independently while maintaining overall system integration
Solution Approach 2:
The patent introduces intermediate connection structures (conductive vias and interconnection layers) that facilitate electrical and mechanical coupling between stacked devices. These intermediaries simplify the integration process by providing standardized interfaces between different acoustic wave device types, reducing the overall manufacturing 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
This approach results in a smaller footprint for acoustic wave filter components, improved performance, and cost-effectiveness by enabling internal and external interconnections between stacked devices, facilitating more efficient radio frequency signal filtering.
Implementation Method 1
A surface acoustic wave resonator can include an interdigital transductor electrode on a piezoelectric substrate. The surface acoustic wave resonator can generate a surface acoustic wave on a surface of the piezoelectric layer
Implementation Method 2
at least a portion of a temperature compensation layer positioned on the interdigital transducer electrode
Data Source
AI summary
An acoustic wave filter component can include a surface acoustic wave device including a first piezoelectric layer, an interdigital transducer electrode on the first piezoelectric layer, and an additional layer, such as a temperature compensation layer, over the interdigital transducer electrode. The acoustic wave filter component can also include a bulk acoustic wave resonator supported by the additional layer. The additional layer may be a layer on which a surface acoustic wave of the surface acoustic wave device will propagate. The bulk acoustic wave resonator may include an air cavity, where a shape of the air cavity is defined in part by the additional layer.