RF Front-End Filter Layout for Stable Resonator Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing filter devices suffer from the influence of external shield electrodes affecting coupling between resonators, leading to unstable filter characteristics.
Innovation Solution
The filter device incorporates a configuration with ground vias that directly couple the shield electrode and ground electrode without passing the common electrode, reducing the influence of external shield electrodes by minimizing signal transfer through the shield electrode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an internal shield electrode is used to mitigate coupling between external shield electrode and common electrode, then filter characteristics stability is improved, but resonators can be coupled to each other via the internal shield electrode through shared ground vias, causing external shield electrode to affect coupling among resonators
Solution Approach 1:
The ground connection path is segmented into two independent paths: one through the common electrode and another directly from the internal shield electrode to the ground electrode via dedicated ground vias. This segmentation prevents signal coupling between resonators through the shield electrode while maintaining the shield electrode's protective function against external interference.
Solution Approach 2:
The harmful coupling path between resonators through the internal shield electrode is extracted and eliminated by providing direct ground connections for the shield electrode. This separates the useful shielding function from the harmful signal coupling path, allowing the shield electrode to protect against external interference without mediating resonator coupling.
2Device complexity
If ground vias are shared between internal shield electrode and resonators, then device complexity is reduced, but signal transfer through the shield electrode increases, making filter characteristics sensitive to external shield electrodes
Solution Approach 1:
The ground via functions are segmented into distinct roles: some vias connect resonators to the common electrode, while other vias directly connect the internal shield electrode to the ground electrode. This functional segmentation ensures that shield electrode ground connections do not serve as signal paths for resonator coupling, eliminating the harmful effect while maintaining manufacturing simplicity.
Solution Approach 2:
The internal shield electrode is provided with dedicated ground vias that act as intermediaries to directly connect it to the ground electrode, bypassing the common electrode and resonator signal paths. This intermediary connection prevents the shield electrode from becoming part of the resonator coupling path while maintaining its electromagnetic shielding function.
Data Source
AI summary
A filter device includes a multilayer body including dielectric layers, an input terminal, an output terminal, a ground terminal, a common electrode, a ground electrode, resonators, a shield electrode, and ground vias. A first ground via couples the shield electrode and the ground electrode via the common electrode. A second ground via directly couples the shield electrode and the ground electrode without passing the common electrode. A first via of a first resonator has one end coupled to the common electrode and another end coupled to the input terminal. A first plate electrode is coupled to the first via and at least partially overlaps the ground electrode when viewed in plan view. A second resonator includes second vias and a second plate electrode. The second plate electrode is coupled to the second via and at least partially overlaps the ground electrode when viewed in plan view in the stacking direction.