Branching Device Inductor Winding Direction for EMI Reduction
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Solution Overview
Problem
Existing branching devices for wireless LANs face challenges in downsizing while reducing electromagnetic interference between LC filter circuits, leading to increased device size, particularly in mobile communication devices.
Innovation Solution
The branching device incorporates a laminated substrate structure with LC filter circuits where the first inductor is wound in one direction and the second inductor is wound in the opposite direction, reducing unnecessary coupling and allowing for a more compact design without the need for additional space between inductors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If via electrodes are provided between inductors to reduce electromagnetic interference, then isolation characteristic is improved, but device size increases due to required space between inductors
Solution Approach 1:
The patent applies the inversion principle by winding the first inductor in a clockwise direction and the second inductor in a counter-clockwise direction. This opposite winding configuration causes the magnetic fields generated by the two inductors to cancel each other out, thereby reducing electromagnetic interference without requiring additional space between the inductors. This resolves the contradiction by achieving improved isolation characteristics while maintaining compact device dimensions.
2Device complexity
If inductors are disposed on the same dielectric layer to reduce device complexity, then manufacturing is simplified, but electromagnetic interference increases due to mutual magnetic field coupling
Solution Approach 1:
The patent maintains the simple structure of disposing both inductors on the same dielectric layer while eliminating electromagnetic interference through opposite winding directions. The first inductor is wound clockwise and the second inductor is wound counter-clockwise, causing their magnetic fields to cancel each other. This approach preserves manufacturing simplicity while eliminating the harmful electromagnetic coupling that would otherwise occur.
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 effectively reduces electromagnetic interference between the LC filter circuits, enabling significant downsizing of the branching device while maintaining effective signal processing across multiple frequency bands.
Implementation Method 1
the first inductor is wound in one direction and the second inductor is wound in the opposite direction, reducing unnecessary coupling
Data Source
AI summary
In a branching device, an LPF includes a first inductor arranged such that some conductor layers from among conductor layers are wound in a clockwise direction, and a second inductor arranged such that a conductor layer from among the conductor layers is wound in an counterclockwise direction. In addition, an HPF includes a third inductor arranged such that conductor layers are wound in the same clockwise direction as the first inductor. Therefore, when a high-frequency signal passes through the LPF, a winding direction is reversed. In addition, when a high-frequency signal passes through the HPF, a winding direction is reversed.