Acoustic Wave Filter Pad Layout for Compact Resonator Arrays
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Solution Overview
Problem
The increasing demand for mobile communication devices has led to frequency band saturation, necessitating smaller and thinner filters for signal separation across various frequency bands, which existing acoustic wave filter technologies struggle to efficiently achieve.
Innovation Solution
The acoustic wave filter device incorporates resonance portions with specific metal pad configurations, including ring portions and passivation layers, to enhance performance and reduce size while maintaining effective signal filtering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the filter size is reduced to meet market demand for smaller devices, then the device dimensions are improved, but the electrical performance and signal filtering capability deteriorate
Solution Approach 1:
The patent introduces a ring portion extending in a radial direction from the metal pad at the edge of the active area, utilizing the dimensional space outside the active region. This allows the electrical connection structure to extend into the peripheral area, maintaining electrical performance while keeping the central active area compact for smaller overall device size.
Solution Approach 2:
The metal pad structure is segmented into two functional parts: a base metal pad within the active area for electrical connection, and a ring portion extending radially outward from the edge of the active area. This segmentation allows the electrical connection function to be distributed across different spatial zones, maintaining performance while optimizing layout.
2Volume of moving object
If the filter thickness is reduced to make thinner devices, then the device dimensions are improved, but the resonance characteristics and filtering efficiency worsen
Solution Approach 1:
The patent employs a composite structure consisting of the piezoelectric layer, lower electrode, upper electrode, membrane layer, and ring portion working together. This composite configuration enhances the resonance characteristics and mechanical strength, allowing for reduced thickness while maintaining filtering efficiency through the synergistic effect of multiple functional layers.
3Area of stationary object
If the active area is reduced to decrease layout area, then the device area is improved, but the electrical connection reliability deteriorates
Solution Approach 1:
The electrical connection structure utilizes the radial dimension extending from the edge of the active area into the peripheral region. By extending the ring portion radially outward, the patent maintains electrical connection reliability without increasing the footprint area, as the extension occurs in the radial direction rather than expanding the overall device area.
Solution Approach 2:
The ring portion acts as an intermediary structure that bridges the electrical connection between the active area and the external circuit. It provides a transition zone that maintains electrical continuity while adapting to the reduced layout area constraints, ensuring reliable signal transmission despite the compact design.
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 allows for improved electrical performance with minimal size reduction, maintaining resonance and anti-resonance point stability and reducing layout area by approximately 16%, while maintaining performance within acceptable dB loss margins.
Implementation Method 1
a piezoelectric layer disposed on at least a portion of the lower electrode
Data Source
AI summary
An acoustic wave filter device includes resonance portions, first and second metal pads. The resonance portions each includes a lower electrode disposed on a substrate, a piezoelectric layer disposed on at least a portion of the lower electrode, and an upper electrode disposed on at least a portion of the piezoelectric layer. The first metal pads are connected to one of the upper electrode and the lower electrode of a corresponding resonance portion among the resonance portions. The second metal pads are disposed outwardly of an active region and connected to the other one of the upper electrode and the lower electrode of adjacent resonant portions among the resonance portions. A ring portion is disposed outwardly of the active region in which the lower electrode, the piezoelectric layer, and the upper electrode overlap is disposed only on a portion of any one of the first and second metal pads.