Multilayer Common Mode Filter with Shielding Conductor for Impedance Matching
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Solution Overview
Problem
Existing common mode choke coils face challenges in maintaining impedance matching between coils and signal lines, leading to difficulties in adjusting differential impedances, which affects the reduction of common mode noise and reflection in electronic components.
Innovation Solution
The electronic component employs a multilayer structure with primary, secondary, and tertiary coils, along with a parallel coil conductor layer, to adjust differential impedances between coils and signal lines, ensuring impedance matching and effective common mode noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the coil structure uses three coils (514, 516, 518) with the ground coil (518) positioned between the signal coils (514, 516), then common mode noise filtering is achieved, but differential impedance matching between signal coils becomes difficult due to unequal capacitance distribution
Solution Approach 1:
The patent introduces a shielding conductor layer between the ground coil and one signal coil, creating non-uniform local electromagnetic shielding. This local modification adjusts the capacitance between specific coils (making C13 ≈ C24) while maintaining the overall three-coil common mode filter structure, thereby resolving the impedance matching issue without sacrificing noise filtering performance
Solution Approach 2:
The shielding conductor layer acts as an intermediary element that mediates the electromagnetic interaction between coils. By positioning this intermediate layer strategically, the patent modifies the capacitance distribution to achieve equal differential impedances while preserving the common mode noise rejection capability of the original three-coil configuration
2Manufacturing precision
If the shielding conductor layer is added to adjust capacitance between coils, then differential impedance matching is improved, but device complexity increases
Solution Approach 1:
The shielding conductor layer is merged with the existing multilayer substrate structure, integrating the impedance matching function into the substrate itself rather than adding separate discrete components. This consolidation achieves differential impedance matching while minimizing increases in overall device complexity
Solution Approach 2:
The shielding conductor layer serves multiple functions simultaneously: it provides electromagnetic shielding, adjusts capacitance between coils for impedance matching, and maintains signal integrity. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity
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 allows for precise adjustment of differential impedances, reducing common mode noise while maintaining signal integrity and minimizing reflection, thus enhancing the performance of the common mode filter.
Implementation Method 1
a first signal S1, a second signal S2, and a third signal S3 are input respectively to the outer electrodes 14a to 14c. The primary coil L1, the secondary coil L2, and the tertiary coil L3 are magnetically coupled
Implementation Method 2
The primary coil L1, the secondary coil L2, and the tertiary coil L3 are magnetically coupled
Data Source
AI summary
An electronic component includes a multilayer body constituted by insulator layers that are laminated in a laminating direction, a primary coil including one or more primary coil conductor layers, a secondary coil including one or more secondary coil conductor layers, and a tertiary coil including one or more tertiary coil conductor layers. The primary coil conductor layers, the secondary coil conductor layers, and the tertiary coil conductor layers are arrayed in the laminating direction. The primary coil, the secondary coil, and tertiary coil constitute a common mode filter, and intervals between two among the one or more primary coil conductor layers, the one or more secondary coil conductor layers, and the one or more tertiary coil conductor layers, every two of those being adjacent to each other in the laminating direction, are not even.