Multi-Rank Memory Self-Refresh Control Logic
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Solution Overview
Problem
In multi-rank memory systems, existing technologies face challenges in efficiently managing self-refresh operations across multiple ranks of DRAM, leading to potential data loss and system instability due to the need for precise control of refresh commands and prevention of spurious signals during self-refresh states.
Innovation Solution
The implementation of an I/O buffer and self-refresh logic that receives and manages chip-select and clock-enable signals to activate and control self-refresh operations across multiple ranks of memory, ensuring that ranks in self-refresh mode are isolated from interrupting signals and maintained through internal refresh commands from non-self-refreshing ranks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If self-refresh operations are implemented in multi-rank memory, then data retention reliability is improved, but control complexity and risk of spurious signal interruption increase
Solution Approach 1:
The memory device is divided into multiple ranks, each with independent chip-select signals (CS0, CS1, CS2, CS3) and clock-enable signals (CKE0, CKE1). This segmentation allows individual ranks to be independently controlled for self-refresh operations, enabling selective refresh of specific ranks while keeping others active, thus improving reliability without requiring system-wide control complexity
Solution Approach 2:
The patent introduces dedicated control logic that acts as an intermediary between the control signals and the memory ranks. This control logic manages the interaction between chip-select signals and clock-enable signals to ensure that self-refresh operations are properly coordinated, preventing spurious interruptions while maintaining the complexity benefits of multi-rank architecture
2Productivity
If multiple ranks are independently refreshed, then operational efficiency is improved, but signal isolation and prevention of spurious operations become more difficult
Solution Approach 1:
Independent chip-select signals (CS0-C3) and clock-enable signals (CKE0, CKE1) are provided for each rank, enabling selective activation and self-refresh of individual ranks. This segmentation allows one rank to perform self-refresh while others remain operational, improving productivity while maintaining signal isolation through dedicated control paths for each rank
Solution Approach 2:
The control logic is designed to prevent spurious operations by establishing proper signal isolation mechanisms before self-refresh operations begin. The dedicated control paths and timing control ensure that refresh operations in one rank do not inadvertently affect other ranks, preemptively preventing harmful signal interference
Data Source
AI summary
Multi-rank memories and methods for self-refreshing multi-rank memories are disclosed. One such multi-rank memory includes a plurality of ranks of memory and self-refresh logic coupled to the plurality of ranks of memory. The self-refresh logic is configured to refresh a first rank of memory in a self-refresh state in response to refreshing a second rank of memory not in a self-refresh state in response to receiving a non-self-refresh refresh command for the second rank of memory.