Asymmetric Common Mode Filter Layout for Low Differential Loss
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Solution Overview
Problem
Existing common mode filters face challenges in achieving higher common mode attenuation and lower differential insertion loss within a limited planar size.
Innovation Solution
A common mode filter design with stacked coil patterns and a magnetic body offset to one side of the inner diameter area, featuring asymmetrical coil conductor distribution and a non-circular magnetic body shape to enhance inductance and reduce differential insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a magnetic body is disposed in the inner diameter area of stacked coil patterns, then common mode attenuation is improved, but differential insertion loss increases
Solution Approach 1:
The magnetic body is disposed asymmetrically within the inner diameter area, with its center offset from the center of the inner diameter area toward the second area. This asymmetric positioning creates different magnetic path lengths and inductance values for common mode and differential mode signals, enabling improved common mode attenuation while maintaining lower differential insertion loss
Solution Approach 2:
The inner diameter area is divided into first and second areas with different functional characteristics. The magnetic body is specifically positioned in the second area, creating localized magnetic field distribution that optimizes the balance between common mode rejection and differential mode signal integrity
2Area of stationary object
If the planar size of the common mode filter is reduced, then device compactness is improved, but achieving high common mode attenuation and low differential insertion loss becomes more difficult
Solution Approach 1:
The patent transitions from a planar coil configuration to a stacked three-dimensional configuration with multiple coil patterns at different levels. This vertical stacking allows the magnetic body to be positioned in the inner diameter area, creating effective common mode filtering while maintaining a compact planar footprint
Solution Approach 2:
The asymmetric positioning of the magnetic body within the stacked coil structure enables optimized magnetic coupling and flux distribution, achieving high filtering performance in a compact form factor by exploiting the three-dimensional space efficiently
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
The design achieves higher common mode attenuation and lower differential insertion loss without increasing the filter's size, by optimizing the magnetic body placement and coil conductor distribution.
Implementation Method 1
a first coil pattern spirally wound in a plurality of turns; a second coil pattern stacked on the first coil pattern through an insulating layer and spirally wound in a plurality of turns
Implementation Method 2
a magnetic body disposed in the inner diameter areas of the first and second coil patterns in a plan view
Data Source
AI summary
Disclosed herein is a common mode filter that includes first and second coil patterns stacked to each other and a magnetic body disposed in the inner diameter areas of the first and second coil patterns. The inner diameter area has a shape in which a size thereof in a first direction is larger than a size thereof in a second direction. The inner diameter area includes a first area positioned on one side in the first direction as viewed from a virtual line and a second area positioned on the other side in the first direction as viewed from the virtual line. The magnetic body is disposed offset to the second area side.