PCB Ground Shielding for Crosstalk Reduction
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Solution Overview
Problem
Conventional printed circuit boards face challenges in reducing size while maintaining signal transmission quality and minimizing crosstalk between signal traces, as reducing the size of the board increases crosstalk severity, and increasing the number of conductive layers raises fabrication costs.
Innovation Solution
A circuit board design featuring a first external wiring layer with signal traces and ground extending portions, and an inner wiring layer with a ground portion and inner signal traces, where the ground portion has an opening region and the inner signal trace is located within it, allowing the ground extending portion and opening region to overlap, reducing crosstalk and board size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the size of the printed circuit board is reduced, then the compactness of the electronic product is improved, but the crosstalk between adjacent signal traces becomes more severe
Solution Approach 1:
The patent utilizes the thickness direction (Z-axis) of the circuit board by creating overlapping ground structures between different conductive layers. The ground extending portions on one layer overlap with opening regions of ground portions on adjacent layers, forming a three-dimensional ground shielding structure that reduces crosstalk without increasing the planar footprint of the board.
Solution Approach 2:
The patent implements a nested ground shielding structure where ground extending portions are positioned within the projection area of opening regions of adjacent ground portions. This nested arrangement creates multiple layers of ground shielding that are contained within each other, maximizing the shielding effect while minimizing the space occupied in the planar direction.
2Object-affected harmful factors
If the space between adjacent signal traces is enlarged to reduce crosstalk, then the signal transmission quality is improved, but the area occupied by the printed circuit board increases
Solution Approach 1:
The patent introduces ground extending portions as intermediary shielding structures between adjacent signal traces on different conductive layers. These ground structures act as mediators that intercept electromagnetic fields and prevent direct coupling between signal traces, thereby reducing crosstalk without requiring increased spacing between signals in the planar direction.
3Object-affected harmful factors
If the quantity of conductive layers is increased to reduce crosstalk, then the signal transmission quality is improved, but the fabrication cost and board size increase
Solution Approach 1:
The patent applies ground shielding structures selectively in specific regions where crosstalk is most severe, rather than providing continuous ground planes across the entire board. The ground extending portions are strategically positioned to overlap with opening regions only in areas requiring enhanced shielding, optimizing the balance between crosstalk reduction and fabrication cost.
Data Source
AI summary
A circuit board and an electronic apparatus using the same are provided. The circuit board includes an integrated-circuit (IC) device arrangement region and an electronic device arrangement region. The circuit board includes a first external wiring layer and an inner wiring layer. The first external wiring layer includes a plurality of first signal traces and a ground extending portion that extend from the IC device arrangement region to the electronic device arrangement region. The inner wiring layer includes a ground portion and an inner signal trace. The ground portion defines an opening region, and the inner signal trace is located in the opening region and extends from a position under the IC device arrangement region to another position under the electronic device region. The ground extending portion and the opening region overlap with each other in a thickness direction of the circuit board.