Cross-Wound Common Mode Filter for High-Frequency Symmetry
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Solution Overview
Problem
Existing common mode filters face challenges in improving mode conversion characteristics in high frequency regions due to disturbances in wire symmetry, particularly near the input side of differential signals.
Innovation Solution
A common mode filter design featuring a pair of wires that cross each other multiple times, with specific layer winding configurations and terminal electrode arrangements to enhance symmetry and reduce parasitic capacitance, allowing for improved bidirectional mode conversion characteristics in high frequency regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pair of wires are made to cross each other after winding of several turns from the wire end portion, then the structure is simpler, but the mode conversion characteristics in high frequency regions cannot be sufficiently improved
Solution Approach 1:
The patent applies preliminary action by making the wires cross each other at the second turn from the end, which is closer to the input side than conventional designs. This early crossing action prevents mode conversion disturbances before they can propagate through the winding, thereby improving high-frequency mode conversion characteristics while maintaining a relatively simple configuration.
Solution Approach 2:
The patent applies local quality by creating a specific crossing configuration at a localized position (second turn from end) rather than uniformly distributing crossings throughout the winding. This localized crossing structure针对性地 addresses the mode conversion issue at the critical input side region without complicating the entire winding structure.
2Manufacturing precision
If the wires are wound by layer winding in an aligned state throughout, then the manufacturing precision is improved, but the wire length and winding core part length increase
Solution Approach 1:
The patent applies partial action by implementing layer winding in an aligned state only at specific portions (first layer winding portion, second layer winding portion, and third layer winding portion) rather than throughout the entire winding. This selective alignment maintains manufacturing precision where it matters most (at the crossing regions) while avoiding excessive wire length and core part length that would result from complete alignment.
Data Source
AI summary
Disclosed herein is a common mode filter that includes first and second wires wound in the same direction around the winding core part. The first and second wires have first to third layer winding portions, a first crossing portion positioned between the first and third layer winding portions, and a second crossing portion positioned between the second and third layer winding portions. The vertical positions of the first and second wires are reversed at least partially between the first and third layer winding portions, and the vertical positions of the first and second wires are reversed at least partially between the second and third layer winding portions.