Multilayer Common Mode Filter Stack for Stable Inductance Control
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Solution Overview
Problem
Existing mobile terminal technologies require a higher-speed data transmission method than the MIPI D-PHY standard, and existing multilayer common mode filters face challenges in maintaining uniform resistance and inductance of coil patterns, leading to changes in inductance characteristics and common mode attenuation.
Innovation Solution
A multilayer common mode filter design with a specific stack configuration including capacitor, floating, and ground patterns, along with coil patterns, to control resonance points and cutoffs, and enhance magnetic coupling, while minimizing via holes and maintaining consistent spacing between coil patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing multilayer common mode filters are used, then data transmission is supported, but inductance characteristics and common mode attenuation change due to non-uniform resistance and inductance of coil patterns
Solution Approach 1:
The filter is divided into multiple stacks (first stack with coil patterns, second stack with capacitor patterns, third stack with ground pattern and inductor pattern). This segmentation allows each stack to be independently designed and optimized, ensuring uniform coil patterns in the first stack while adding functional elements in subsequent stacks without disrupting the original coil uniformity.
Solution Approach 2:
The patent transitions from a two-dimensional planar layout to a three-dimensional stacked architecture. By arranging capacitor patterns, ground patterns, and inductor patterns in vertical layers beneath the coil patterns, the design achieves uniform inductance characteristics through precise spatial positioning in the vertical dimension while maintaining coil pattern uniformity in the horizontal dimension.
2Speed
If higher-speed data transmission is implemented, then data transmission speed increases, but noise current in common mode increases requiring enhanced filtering
Solution Approach 1:
Capacitor patterns are introduced as intermediary elements between the coil patterns and the ground pattern. These capacitors provide a low-impedance path for common mode noise current to reach ground, effectively filtering high-frequency noise generated by higher-speed data transmission while allowing differential mode signals to pass through unchanged.
Solution Approach 2:
The patent modifies the electrical parameters of the filtering circuit by adding capacitor patterns with specific capacitance values and inductor patterns with specific inductance values. These parameter changes create resonant circuits that target specific noise frequencies generated by high-speed transmission, enabling effective common mode rejection while maintaining signal integrity.
3Reliability
If additional filtering elements are added to control resonance and cutoff, then filtering performance improves, but device complexity increases
Solution Approach 1:
The patent merges multiple filtering functions into a single integrated stacked structure. The first stack containing coil patterns, the second stack containing capacitor patterns, and the third stack containing ground and inductor patterns are combined vertically to form one compact filter unit that provides both common mode rejection and differential mode signal transmission in a single device.
Solution Approach 2:
The stacked configuration serves multiple functions simultaneously: the coil patterns provide inductance for differential mode signal transmission, the capacitor patterns provide capacitance for common mode noise filtering, the ground pattern provides a reference potential and noise sink, and the inductor pattern provides additional inductance for resonance control. This multi-functionality achieves superior filtering performance without proportionally increasing 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
The design achieves uniform resistance and inductance of coil patterns, expands attenuation bands, minimizes inductance variations, and enhances electromagnetic coupling, thereby supporting higher-speed data transmission with reduced manufacturing complexity.
Implementation Method 1
a floating pattern disposed under the plurality of capacitor patterns, and configured to form additional capacitance by overlapping the plurality of capacitor patterns
Implementation Method 2
an inductor pattern disposed between the floating pattern and the ground pattern
Implementation Method 3
a first stack provided with a first coil pattern, a second coil pattern, and a third coil pattern
Data Source
AI summary
A multilayer common mode filter of the present disclosure has a filter stack configured by stacking, underneath a coil stack comprising a plurality of coils configuring mutually different channels, a stack provided with a capacitor pattern, a floating pattern, an inductor pattern, and a ground pattern, wherein resonance frequency characteristics may be changed according to the inductor pattern.