Multi-rank Memory Module Signal Hub Placement
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Solution Overview
Problem
In multi-rank memory modules, ensuring proper arrangement and connection of memory devices across multiple ranks to maintain data signal quality and integrity is challenging, particularly in balancing signal loads and reducing signal path differences.
Innovation Solution
A multi-rank memory module design with memory devices organized in three ranks across both sides of a module board, using data/strobe signal hubs positioned away from the edge to reduce signal path differences and reflection, and register devices to provide balanced control/address signals, along with flexible and rigid daughterboards for improved signal routing and integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory devices are organized in multiple ranks across both sides of the module board, then memory capacity and performance are improved, but signal path length differences and reflection increase
Solution Approach 1:
Signal hubs are introduced as intermediary components between the memory devices in different ranks and the module connectors. These hubs act as central connection points that equalize signal path lengths to multiple memory devices, reducing signal path differences and reflection while maintaining support for multiple memory ranks across both sides of the module board.
Solution Approach 2:
The patent utilizes the third dimension (vertical stacking) by mounting memory devices on both sides of the module board and organizing them into multiple ranks. This dimensional approach increases memory capacity without significantly increasing the footprint area, while signal hubs positioned away from the edge manage the resulting signal path variations.
2Reliability
If data/strobe signal hubs are positioned away from the edge of the module board, then signal reflection is reduced and signal quality is improved, but signal path length differences may increase
Solution Approach 1:
Signal hubs are positioned at specific locations away from the module board edge where they can optimally serve groups of memory devices. Each signal hub is locally optimized to reduce reflection for its connected memory devices, and the overall design balances signal path lengths across different ranks through strategic positioning rather than uniform placement.
3Productivity
If multiple memory devices are connected to respective module connectors, then memory bandwidth and performance are improved, but load balancing on control/address signals becomes difficult
Solution Approach 1:
The memory module is segmented into multiple ranks, with each rank connected to module connectors through dedicated signal paths. This segmentation allows control/address signals to be distributed more evenly across different rank groups, simplifying load balancing while maintaining high memory bandwidth through parallel access to multiple ranks.
Data Source
AI summary
A multi-rank memory module is operable in a memory system with a memory controller. The memory module according to one embodiment comprises at least one module board, memory devices organized in three ranks, and at least one register device providing control/address signals to the memory devices. Arrangement of the ranks on the at least one module board are made to balance memory device loadings on the C/A signals, and data/strobe signal hubs are designed to provide better alignment of different data bits in a data signal and to reduce reflection from discrete components disposed near an edge of the module board, resulting in improved signal quality and integrity.