Multilayer SAW Filter Ground Via Structure for Lower Parasitic Inductance
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Solution Overview
Problem
Acoustic wave filters, particularly multi-mode surface acoustic wave filters, face challenges with parasitic inductance and limited ground connection flexibility due to traditional metal bridge structures, which affect performance and placement in radio frequency applications.
Innovation Solution
The use of through-substrate vias provides a direct ground connection for multi-mode surface acoustic wave resonators or filters, reducing parasitic inductance and allowing for flexible placement by eliminating the need for metal bridge structures, thereby enhancing the manufacturing process and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional metal bridge structures are used to connect resonators to ground, then the structure provides ground connection, but parasitic inductance increases and ground connection flexibility is limited
Solution Approach 1:
The patent extracts and removes the traditional metal bridge structure from the system, replacing it with through-substrate vias that directly connect the resonator to the ground plane. This elimination of the intermediate metal bridge structure removes the source of parasitic inductance while maintaining the essential ground connection function.
Solution Approach 2:
The patent transitions from a planar metal bridge connection to a vertical through-substrate via connection. By changing the dimensional approach from horizontal routing to vertical penetration through the substrate, the design achieves lower inductance and improved ground connection flexibility without compromising reliability.
2Reliability
If traditional metal bridge structures are used, then ground connection is provided, but device placement flexibility is limited
Solution Approach 1:
The patent enables flexible device placement by transitioning from planar metal bridge routing to vertical through-substrate via connections. This dimensional change allows resonators to be positioned anywhere on the substrate while maintaining reliable ground connections, significantly improving placement adaptability.
Solution Approach 2:
The through-substrate via structure serves multiple functions: it provides ground connection, enables flexible placement, and simplifies manufacturing. This universal approach replaces the specialized metal bridge structure with a more versatile solution that works across different device configurations.
3Object-generated harmful factors
If through via ground connections are implemented, then parasitic inductance is reduced and placement flexibility is improved, but via fabrication complexity increases
Solution Approach 1:
The patent merges the ground connection function with the substrate structure itself by creating through vias during substrate fabrication. This integration combines multiple functions into a single manufacturing process, reducing overall complexity despite the added via formation step.
Solution Approach 2:
The through vias are formed during the substrate fabrication process before final assembly. This preliminary action incorporates the ground connection structure into the substrate itself, simplifying subsequent assembly steps and reducing 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 solution improves the attenuation performance and reduces parasitic inductance, allowing for better filter placement and simpler manufacturing, resulting in improved radio frequency signal filtering capabilities.
Implementation Method 1
The use of through-substrate vias provides a direct ground connection for multi-mode surface acoustic wave resonators or filters, reducing parasitic inductance
Implementation Method 2
One or more surface acoustic wave resonators or filters are disposed over the multi-layer piezoelectric substrate, the one or more surface acoustic wave resonators or filters including a multi-mode surface acoustic wave resonator or filter
Implementation Method 3
a multi-layer piezoelectric substrate disposed over a first side of the support substrate
Data Source
AI summary
A packaged acoustic wave component includes a support substrate, a multi-layer piezoelectric substrate disposed over a first side of the support substrate, one or more metal layers disposed on a second side of the support substrate that is opposite the first side of the support substrate, and one or more surface acoustic wave resonators or filters disposed over the multi-layer piezoelectric substrate. The one or more surface acoustic wave resonators or filters include a multi-mode surface acoustic wave resonator or filter (e.g., dual mode surface acoustic wave resonator or filter). One or more vias extend through the support substrate and electrically connect the multi-mode surface acoustic wave resonator or filter and the one or more metal layers to provide a ground connection for the multi-mode surface acoustic wave resonator or filter, while reducing parasitic inductance.