Multiband Filter Inductor Layout for Low Magnetic Coupling
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Solution Overview
Problem
In existing filter devices with LC filters, magnetic coupling between adjacent inductors leads to a decrease in the Q factor and deterioration of isolation, affecting filter characteristics.
Innovation Solution
The filter device is configured such that the inductors of different filters are positioned to avoid magnetic interference by using vertical coils with plate electrodes and vias in one filter and planar coils with winding axes perpendicular to the other filter, ensuring non-intersecting imaginary lines between their extending directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If inductors of different filters are disposed adjacent to each other to reduce device size, then integration density is improved, but magnetic coupling between inductors increases causing Q factor decrease and isolation deterioration
Solution Approach 1:
The patent transitions from planar inductor layouts to three-dimensional vertical coil structures. By extending inductors in the vertical dimension with plate electrodes and vias through multiple substrate layers, the design achieves higher integration density while the vertical orientation naturally reduces magnetic coupling between adjacent inductors on different layers
Solution Approach 2:
The patent introduces magnetic shielding plates positioned between adjacent inductors of different filters. These shielding plates act as intermediaries that block or redirect magnetic flux, preventing harmful magnetic coupling while allowing the inductors to remain in close proximity for compact device integration
2Device complexity
If inductors are placed close together to improve integration, then device complexity is reduced, but magnetic interference increases leading to Q factor decrease
Solution Approach 1:
The patent employs vertical coils that extend through multiple substrate layers using plate electrodes and vias. This three-dimensional configuration allows inductors to be placed closer together in the planar direction while maintaining adequate magnetic isolation through the vertical separation and orientation, thus reducing magnetic interference and preserving Q factor
Solution Approach 2:
Magnetic shielding plates are strategically positioned between adjacent inductors to mediate the magnetic interaction. These shields redirect magnetic flux paths, preventing energy loss through unwanted coupling while allowing compact inductor placement for simplified device structure
3Area of stationary object
If adjacent inductors are used to reduce device area, then space utilization is improved, but isolation between filters deteriorates due to magnetic coupling
Solution Approach 1:
The patent utilizes vertical coils extending through multiple substrate layers to achieve compact planar footprint. The vertical orientation and multi-layer separation provide natural magnetic isolation between adjacent filters, enabling high space utilization while maintaining filter isolation performance
Solution Approach 2:
Magnetic shielding plates are inserted between adjacent inductors of different filters to block magnetic flux interference. These shields act as mediators that prevent harmful magnetic coupling, allowing inductors to be positioned close together for compact device area while maintaining adequate isolation
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 reduces magnetic coupling, improving the Q factor and enhancing filter characteristics by minimizing interference between inductors, thereby improving insertion loss and attenuation characteristics.
Implementation Method 1
an inductor included in the first filter is a vertical coil which includes a plate electrode and a via extending in the normal direction of the body
Implementation Method 2
In the second filter, the at least one inductor facing the first range is a planar coil with a winding axis extending in the normal direction of the body
Implementation Method 3
a magnetic flux penetrating an air core diameter of one inductor interferes with the other inductor. Therefore, magnetic coupling between the two inductors may be caused
Data Source
AI summary
A filter includes a body and first and second filters with pass bands different from each other. In the body, an inductor of the first filter is in a first range, and an inductor of the second filter is in a second range. The inductor in the first filter is a vertical coil including a plate electrode and a via extending in a normal direction of the body. In the second filter, the inductor facing the first range is a planar coil with a winding axis in the normal direction of the body. As seen in plan view in the normal direction of the body, an imaginary line from an extending-direction center of the plate electrode of the first filter in a direction perpendicular or substantially perpendicular to the extending direction does not intersect with the inductor of the second filter.