PCB Ground Via Lattice for Crosstalk Reduction
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Solution Overview
Problem
Crosstalk between transmission lines on printed circuit boards increases with higher bit rates and closer spacing, posing challenges for high-speed electronic signal transmission while also limiting design flexibility and packaging density.
Innovation Solution
A printed circuit board design featuring a strip line structure with strategically arranged ground vias in an equilateral triangular or square lattice pattern, which electrically connects ground conductor layers and reduces electromagnetic wave propagation, thereby minimizing crosstalk and allowing for higher bit rates and denser packaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If transmission lines are disposed close to each other to reduce board width, then packaging density is improved, but crosstalk between transmission lines increases
Solution Approach 1:
The patent introduces ground vias as intermediary elements positioned between adjacent transmission lines. These ground vias act as mediators that provide shielding and reference potential, thereby reducing the harmful electromagnetic coupling (crosstalk) between closely spaced transmission lines while allowing compact board layout.
Solution Approach 2:
The patent extracts the ground reference function from the traditional continuous ground plane and implements it through discrete ground vias positioned strategically between transmission lines. This extraction allows for selective placement of grounding elements that provide crosstalk reduction without requiring extensive ground areas, thus enabling compact design.
2Area of stationary object
If transmission lines are disposed close to each other to reduce board width, then packaging density is improved, but design flexibility deteriorates
Solution Approach 1:
The patent segments the traditional continuous ground plane into discrete ground via elements positioned between specific transmission lines. This segmentation provides design flexibility by allowing selective placement of ground vias only where crosstalk reduction is needed, while leaving other areas free for additional circuit elements or alternative routing options.
Solution Approach 2:
The patent applies local quality by positioning ground vias specifically between adjacent transmission lines where crosstalk is a concern, rather than implementing a uniform ground structure throughout. This localized approach provides crosstalk reduction exactly where needed while maintaining design flexibility in other regions of the circuit board.
3Speed
If bit rate is increased for faster signal transmission, then transmission speed is improved, but crosstalk increases
Solution Approach 1:
The ground vias serve as intermediary shielding elements that become increasingly important at higher bit rates. As signal frequency increases, the ground vias provide more effective reference potential and electromagnetic shielding, counteracting the tendency for crosstalk to increase with higher transmission speeds.
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 effectively reduces crosstalk between transmission lines, enabling higher bit rates up to 56 Gbit/s and improving packaging density by minimizing electromagnetic interference and optimizing signal transmission quality.
Implementation Method 1
a plurality of ground vias formed surrounding the signal via and extending through the first dielectric layer, for electrically connecting the first ground conductor layer and the second ground conductor layer
Implementation Method 2
a strip line is superior in reduction of crosstalk between adjacent transmission lines... it is theoretically possible to eliminate far-end crosstalk completely as crosstalk due to an electric field and crosstalk due to a magnetic field completely offset to each other
Data Source
AI summary
A printed circuit board includes a first signal line inside a first dielectric layer; a first ground conductor layer and a second ground conductor layer; a second signal line disposed on the first ground conductor layer; a signal via for connecting the first signal line and the second signal line; and ground vias formed surrounding the signal via. The ground vias include first ground vias formed at respective first points, second ground vias formed at respective second points. The first points are placed on the line of a first polygon, and the second points are placed on the line of a second polygon, and the distances between adjacent first points and those between adjacent second points are all equal to or shorter than a first distance, and at least one second point is placed within the first distance from each of the adjacent first points.