Common Mode Filter Winding Asymmetry for Reflection Characteristics
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Solution Overview
Problem
Common mode filters with crossing wires experience deterioration in reflection characteristics due to positional inversion and asymmetry, leading to unbalanced capacitance and poor high-frequency performance.
Innovation Solution
A common mode filter design featuring a winding core with symmetric first and second winding blocks, where the first and second wires cross each other in specific areas, and a non-layer part is introduced to adjust the number of turns, enhancing symmetry and reflection characteristics by altering the capacitance component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pair of wires are made to cross each other on the way to enhance symmetry between differential signals, then high-frequency characteristics are improved, but the positional relationship between the wires is inverted requiring a second crossing which may cause deterioration of reflection characteristics
Solution Approach 1:
The winding core part is divided into three distinct winding areas (first, second, and third winding areas) along the axial direction. The first and second wires are wound in different patterns in each area: they are wound separately in the first and second winding areas, and cross each other in the third winding area. This segmentation allows optimization of both high-frequency characteristics and reflection characteristics by controlling the winding pattern in each specific area.
Solution Approach 2:
Different winding patterns are applied to different locations of the winding core part. Specifically, the wires are wound in a first pattern (separate winding) in the first and second winding areas, and in a second pattern (crossing winding) in the third winding area. This local differentiation of winding quality allows the filter to achieve both improved high-frequency characteristics through the crossing section and maintained reflection characteristics through the separate winding sections.
2Reliability
If the first and second wires cross each other in the third winding area, then symmetry between differential signals is enhanced, but asymmetry in the number of turns between winding layers causes unbalance and deteriorates reflection characteristics
Solution Approach 1:
The invention intentionally introduces asymmetry in the form of a non-layer part where both the first and second wires are positioned in the first winding layer, creating a difference in the number of turns between the first and second winding layers. This controlled asymmetry compensates for the unbalance caused by the crossing configuration, thereby improving reflection characteristics while maintaining the symmetry benefits of the crossing wires.
Solution Approach 2:
The invention changes the winding parameters by creating a non-layer part with a specific number of turns (different from the layer part). This parameter change in the winding structure allows adjustment of the electrical characteristics to compensate for unbalance, thereby improving reflection characteristics without sacrificing the symmetry enhancement provided by the wire crossing.
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 improves reflection characteristics and high-frequency performance by balancing the capacitance and positional relationship between wires, specifically in the 10 MHz to 400 MHz band, and maintains symmetry to restore the original positional relationship.
Implementation Method 1
a capacitance component generated between the first and second wires changes with respect to that when the first and second winding blocks are completely symmetric
Data Source
AI summary
Disclosed herein is a common mode filter that includes: a winding core part including first and second winding areas and a third winding area positioned between the first and second winding areas; and first and second wires wound in a same direction around the winding core part. The first and second wires constitute a first winding block wound in the first winding area and a second winding block wound in the second winding area. The first and second wires cross each other in the third winding area. Each of the first and second winding blocks has first and second winding layers. The difference in a number of turns between the first winding layer and the second winding layer is larger in the first winding block than in the second winding block.