Common Mode Noise Filter With Deviated Coil Axes
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Solution Overview
Problem
Conventional common mode noise filters suffer from poor magnetic coupling balance between coils, leading to signal degradation in differential signals, especially when applied to three-wire differential signal lines, due to the placement of coils which results in weak magnetic coupling between coils that are far apart.
Innovation Solution
The proposed common mode noise filter design includes non-magnetic layers with coil conductors arranged in a laminating direction, where adjacent coils are magnetically coupled by adjusting the distance between them, and deviating the winding axes of coil conductors on odd-numbered layers from those on even-numbered layers in a perpendicular direction to balance magnetic coupling among the coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If three independent coils are disposed in the laminating direction, then the common mode noise filter can eliminate common mode noise, but the magnetic coupling balance between coils deteriorates
Solution Approach 1:
The patent applies asymmetry by deviating the winding axes of coil conductors on odd-numbered layers from those on even-numbered layers in a direction perpendicular to the laminating direction. This asymmetric arrangement compensates for the weak magnetic coupling between distant coils (coil 2 and coil 4) while maintaining strong coupling between adjacent coils, thereby achieving balanced magnetic coupling across all three coils without sacrificing common mode noise elimination capability
2Device complexity
If coils are placed far apart to reduce interference, then device complexity is reduced, but magnetic coupling between coils weakens
Solution Approach 1:
The patent utilizes the perpendicular dimension (direction perpendicular to laminating direction) to adjust magnetic coupling. By deviating winding axes in this additional dimension, the patent achieves balanced magnetic coupling among all three coils while maintaining a compact laminated structure, effectively using spatial arrangement in multiple dimensions to solve the coupling balance problem
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 enhances the balance of magnetic coupling among coils, improving the elimination of common mode noise and maintaining the quality of differential signals by adjusting the magnetic coupling between coils, thereby increasing the impedance and noise elimination capability.
Implementation Method 1
When a common mode noise is input to this structure, magnetic fields generated in coils 2 to 4 emphasize each other, and allow coils 2 to 4 to function as an inductor for eliminating the noise
Data Source
AI summary
A common mode noise filter includes plural non-magnetic layers stacked in a laminating direction, and first, second, and third coil conductors constituting first, second, and third coils which are formed on the non-magnetic layers and are independent from one another. The first and third coil conductors deviate from the second coil conductor in a direction perpendicular to the laminating direction.