Expansion Card Interface Layout for Reduced High-Frequency Reflections
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional expansion card interfaces for high-frequency signals suffer from reduced signal margins due to signal and ground stubs causing reflections, which worsen with increasing stub lengths.
Innovation Solution
The expansion card interface design modifies the positions of ground pins such that they are not adjacent to signal pins, maintaining electrical connectivity while reducing interference, thereby minimizing signal stub reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ground pins are positioned adjacent to signal pins to provide grounding, then electrical connection is improved, but signal reflections increase and signal margin decreases
Solution Approach 1:
The patent extracts the ground pin from its conventional position adjacent to the signal pin and relocates it to a position not adjacent to the signal pin. This separation removes the harmful interaction between ground pins and signal pins, eliminating signal reflections while maintaining the necessary electrical connection through alternative grounding paths via other ground pins or substrate planes.
Solution Approach 2:
The patent segments the grounding function by using multiple ground pins distributed across the interface rather than relying on a single ground pin adjacent to each signal pin. This segmentation allows the signal pin to extend fully to the substrate edge for optimal signal transmission while other ground pins provide distributed grounding without causing reflections.
2Reliability
If signal pins extend to the edge of the substrate for optimal signal transmission, then signal margin improves, but ground pin positioning becomes constrained
Solution Approach 1:
The patent resolves the positioning constraint by utilizing the lateral dimension of the substrate edge. Ground pins are positioned along the edge of the substrate in a location that is not adjacent to any signal pin, effectively using the perimeter space to accommodate grounding requirements without interfering with signal pin extension to the edge.
3Object-generated harmful factors
If ground pins are made shorter to reduce interference, then signal reflections decrease, but grounding effectiveness may be compromised
Solution Approach 1:
The patent implements a distributed grounding system where multiple ground pins collectively provide the grounding function. Each ground pin can be optimized in length to minimize reflections, while the ensemble of ground pins working together maintains overall grounding effectiveness through redundant pathways and distributed capacitance to ground planes.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The present disclosure describes an expansion card interface for a printed circuit board. The expansion card interface includes a substrate having an edge. The expansion card interface further includes a plurality of signal pins configured to communicate one or more signals to and from the printed circuit board. The expansion card interface further includes a plurality of ground pins adjacent to the plurality of signal pins configured to provide a ground. At least one signal pin of the plurality of signal pins extends closer to the edge of the substrate than at least one ground pin of the plurality of ground pins.