Noise Filter Segmented Ground Patterns for EMC
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Solution Overview
Problem
Conventional noise filters fail to effectively attenuate noise across both low and high frequency bands due to stray static capacitance, leading to degradation of noise attenuation characteristics and mixing of radiation noise into the main circuit pattern, which compromises EMC performance.
Innovation Solution
The noise filter design incorporates multiple line bypass capacitors and board ground patterns separated on a multilayer filter board, with specific spacing and connection to a ground plane, to prevent noise current paths that cause degradation, and to ground radiation noise effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If common board ground pattern is used, then manufacturing is simplified, but radiation noise mixing into main circuit occurs
Solution Approach 1:
The continuous board ground pattern is segmented into multiple separate ground patterns positioned at specific locations. This segmentation disrupts the continuous ground path that would allow radiation noise to couple into the main circuit, while still providing adequate grounding through the distributed ground patterns.
Solution Approach 2:
The separate ground patterns act as intermediary elements between the main circuit and the ground plane. They provide controlled capacitance coupling to ground for noise filtering while their discontinuous arrangement prevents radiation noise from coupling efficiently into the main circuit through the ground system.
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 design improves noise attenuation characteristics across a broader frequency range without degrading high-frequency performance and prevents radiation noise from mixing into the main circuit, enhancing overall EMC performance.
Implementation Method 1
improves the noise attenuation characteristics using the stray static capacitance generated between the common mode choke coils and the electric conductor as a line bypass capacitor that bypasses noise to the ground potential part
Implementation Method 2
a noise filter including common mode choke coils, capacitors, and the like
Data Source
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AI summary
A noise filter inserted between the power source side and the load side of a main circuit for which noise is reduced to attenuate noise of the main circuit using a filter circuit including the coil and the capacitor. In the noise filter, the board ground pattern is separated into a plurality of board ground patterns, the separated board ground patterns are connected to a common ground member present outside the board, the separated board ground patterns are formed as solid patterns, and adjacent board ground patterns of the separated board ground patterns are disposed so as to have a spacing equal to or less than a predetermined distance.