Differential Transmission Line Ground Layer Segmentation for Noise Reduction
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Solution Overview
Problem
Existing differential transmission lines face challenges in reducing common mode noises, particularly in curved sections, which lead to signal distortion and electromagnetic radiation, as previous methods have not effectively addressed the issue of signal interference.
Innovation Solution
The proposed solution involves a differential transmission line and wiring substrate design with a metal conductor removal block in specific projection areas of the ground layer corresponding to curved sections of the transmission lines, adjusting impedance to minimize common mode noise by removing metal conductors in strategic regions between the first and second transmission lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal conductor removal block is formed in the ground layer at curved sections of the differential transmission line, then common mode noises are reduced and signal integrity is improved, but the device structure becomes more complex and manufacturing difficulty increases
Solution Approach 1:
The ground layer is segmented by removing specific metal conductor portions at curved sections, creating isolated ground regions. This segmentation prevents common mode noise propagation while maintaining ground functionality in straight sections, resolving the contradiction between noise reduction and structural simplicity.
Solution Approach 2:
The ground layer structure is modified locally only at curved sections where noise problems occur, rather than changing the entire ground layer. The metal conductor removal blocks are positioned specifically at projection areas of curved sections, providing targeted noise reduction while preserving the overall simplicity of the ground layer design.
2Object-generated harmful factors
If metal conductors are removed from the ground layer to reduce common mode noises, then electromagnetic radiation is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
The metal conductor removal blocks are designed and positioned in advance during the PCB layout phase, with clear projection area definitions relative to curved sections. This preliminary planning establishes precise positioning criteria that guide the manufacturing process, reducing the actual manufacturing precision burden while achieving electromagnetic radiation reduction.
Solution Approach 2:
The solution addresses the positioning precision issue by introducing a dimensional reference system based on projection areas. The removal blocks are positioned based on their relationship to the projection areas of curved sections, providing a clear spatial reference that simplifies manufacturing alignment and reduces precision requirements.
3Reliability
If the ground layer is modified with metal conductor removal blocks, then impedance is adjusted to minimize common mode noise, but the device complexity increases
Solution Approach 1:
The ground layer impedance is adjusted locally at curved sections through metal conductor removal blocks, rather than modifying the entire ground layer structure. This localized approach achieves common mode noise reduction while maintaining the simplicity of the overall ground layer configuration, as most of the ground layer remains unchanged.
Solution Approach 2:
The curvature of the transmission line, which inherently causes impedance discontinuity and common mode noise, is converted into a beneficial design feature. The metal conductor removal blocks are strategically positioned at curved sections to exploit the geometric characteristics, transforming the harmful curvature effect into a controlled impedance adjustment mechanism that reduces noise while maintaining design simplicity.
Data Source
AI summary
A differential transmission line and a wiring substrate are provided. The differential transmission line includes a ground layer, a dielectric layer, a first transmission line, and a second transmission line. The ground layer is formed of a metal conductor. The dielectric layer is disposed on the ground layer. The first transmission line and the second transmission line are disposed on the dielectric layer. A metal conductor removal block is distributed in at least a portion of at least one of a first projection area of the ground layer on which to project the first transmission line and a second projection area of the ground layer on which to project the second transmission line. A metal conductor is provided in a region between the first projection area and the second projection area of the ground layer.