Compact Coil Filter Layout to Mitigate Magnetic Coupling
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Solution Overview
Problem
When filter devices are reduced in size, the increased magnetic field coupling between coil elements compromises their ability to achieve necessary attenuation characteristics.
Innovation Solution
The filter device incorporates a spiral-shaped first coil and a helical-shaped second coil, with specific electrode patterns and capacitors, to mitigate magnetic field coupling and maintain attenuation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the filter device is reduced in size, then the device size is decreased, but the magnetic field coupling between coil elements increases
Solution Approach 1:
The patent applies asymmetry by using different coil shape configurations - a spiral-shaped first coil and a helical-shaped second coil. This asymmetric design between the two coils reduces magnetic field coupling compared to using identical coil shapes, thereby resolving the contradiction between miniaturization and magnetic coupling reduction.
Solution Approach 2:
The patent utilizes three-dimensional space by stacking the spiral-shaped first coil and helical-shaped second coil in different layers within the insulator. This dimensional arrangement reduces the planar footprint while maintaining adequate spatial separation between coils, achieving size reduction without excessive magnetic coupling.
2Volume of moving object
If the filter device is reduced in size, then the device size is decreased, but the attenuation characteristics deteriorate
Solution Approach 1:
The asymmetric combination of spiral and helical coil shapes creates different magnetic field distribution patterns that interfere destructively with each other, reducing unwanted coupling effects. This maintains the filter's attenuation characteristics even when the overall device size is reduced.
Solution Approach 2:
The patent changes the geometric parameters of the coils by using fundamentally different shapes (spiral vs. helical) rather than varying only dimensions of identical shapes. This parameter change in coil configuration allows maintaining electrical performance while reducing physical size.
3Volume of moving object
If the two coil elements are closer together, then the device size is reduced, but the magnetic field coupling increases
Solution Approach 1:
By making the coil shapes asymmetric (spiral vs. helical), the magnetic field lines from one coil do not align optimally with the other coil, reducing the coupling force between them even when positioned close together in the miniaturized device.
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 enables the filter device to achieve necessary attenuation characteristics despite being reduced in size, with improved transmission characteristics and reduced insertion loss.
Implementation Method 1
the influence of magnetic field coupling between the two coil elements becomes larger
Data Source
AI summary
A filter device includes an insulator, a first coil, a first outer electrode, a second coil, a second outer electrode, a first electrode pattern, a second electrode pattern, and a third outer electrode. The insulator includes a pair of main surfaces facing each other and a side surface connecting the main surfaces. The first coil is a spiral coil in the insulator. The second coil is a helical coil in the insulator and overlapping with at least a portion of the first coil when viewed in plan view from one main surface side.