H-Cable All-to-All PCB Connectivity for Signal Integrity
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Solution Overview
Problem
High-speed differential input/output interfaces in computer systems face challenges in maintaining communication bandwidth and all-to-all connectivity due to signal loss and physical space constraints, especially as the number of nodes increases beyond 1024.
Innovation Solution
The use of H-cables (such as double-H or quad-H cables) to connect multiple printed circuit boards (PCBs) in an all-to-all configuration, reducing PCB route-lengths and cable assembly size, thereby minimizing the need for retimers and repeaters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct board-to-board connections are used to connect PCBs, then connectivity is achieved, but the physical space required increases and signal loss increases due to longer route lengths
Solution Approach 1:
The patent implements nested H-cable assemblies where multiple cables are bundled together in a hierarchical structure. The H-cables connect switches to connectors in a nested configuration, allowing multiple signal paths to be contained within a compact cable assembly. This nesting approach reduces the overall physical space required while maintaining multiple connection paths between PCBs.
2Length of stationary object
If retimers/repeaters/redrivers are added to extend signal reach, then signal loss is compensated, but latency increases and power consumption increases
Solution Approach 1:
The patent converts the harmful effect of signal loss into a benefit by carefully designing H-cable assemblies with controlled impedance and optimized routing that minimize signal degradation. Instead of adding retimers to compensate for loss, the design ensures that the cable assemblies themselves maintain signal integrity over the required distances, turning the challenge of signal loss into an opportunity for optimized cable design that avoids the latency penalties of active compensation devices.
3Adaptability or versatility
If more connectors and cables are added to support higher node counts, then all-to-all connectivity is achieved, but device complexity increases and manufacturing difficulty increases
Solution Approach 1:
The patent segments the connectivity system into modular H-cable assemblies, each handling a specific subset of connections between PCBs. Rather than implementing a monolithic complex cabling system, the solution divides the connectivity function into repeatable modular units that can be systematically assembled. Each H-cable assembly contains a defined set of connectors and routing patterns that can be replicated to support scaling to higher node counts while maintaining manageable complexity through standardization.
4Reliability
If traditional cabling solutions are used to connect PCBs, then connectivity is achieved, but cable assembly size increases and manufacturability decreases
Solution Approach 1:
The patent merges multiple individual cable connections into integrated H-cable assemblies that combine multiple signal paths, power lines, and ground returns into a single unified cable structure. This consolidation reduces the total number of separate cable assemblies required, simplifies the manufacturing process by reducing the number of connector installations, and improves reliability by ensuring matched impedance characteristics across all signal paths within each H-cable assembly.
Data Source
AI summary
A computer supernode including two or more printed circuit boards that each include two or more compute nodes, two or more switches, and two or more connectors. The compute nodes are connected to each switch, and the switches are connected to each connector by a number of lanes. The computer supernode also includes two or more H-cables connecting the printed circuit boards together in an all-to-all configuration. Each H-cable connects a connector of a printed circuit board to a connector in each of two or more other printed circuit boards.