Concurrent Row Refresh and Activate in Memory Banks
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Solution Overview
Problem
Existing memory systems face increased latency and potential data loss due to the need to perform refresh operations concurrently with host-initiated access operations, as refresh operations are typically performed in the background and can interfere with access operations.
Innovation Solution
The system supports concurrent row refresh and activate by opportunistically refreshing memory cells in a bank while performing host-initiated access operations within the same bank. This is achieved by selecting a second row to refresh that is greater than a threshold distance away from the first row being accessed, allowing both operations to be performed simultaneously.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refresh operations are performed in the background, then data reliability is maintained, but latency for host-initiated access operations increases
Solution Approach 1:
The patent merges refresh operations with host-initiated access operations by allowing them to execute concurrently on different rows. The memory system selects a second row for refresh that is greater than a threshold distance away from the first row being accessed, enabling both operations to proceed simultaneously without interference, thus eliminating the latency penalty associated with sequential execution while maintaining data reliability
Solution Approach 2:
The patent implements preliminary action by pre-selecting and preparing the second row for refresh before the host-initiated access operation completes. The memory system determines which row to refresh in advance and ensures the row is ready for concurrent operation, allowing the refresh to begin before the host access finishes and reducing overall latency
2Loss of time
If refresh operations are performed concurrently with host-initiated access operations, then latency is reduced, but the complexity of coordinating operations increases
Solution Approach 1:
The patent applies local quality by treating different rows differently based on their proximity to the accessed row. Rows greater than a threshold distance away from the accessed row are eligible for concurrent refresh, while rows closer than the threshold are excluded. This localized differentiation simplifies the coordination logic by establishing a clear spatial boundary for concurrent operations
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of a row selection logic that mediates between the host access operation and the refresh operation. The memory system uses this intermediary to determine which row to refresh based on the threshold distance criterion, coordinating the two operations without requiring complex synchronization protocols
3Ease of operation
If the same row is accessed for both host operation and refresh, then operation simplicity is maintained, but data loss may occur
Solution Approach 1:
The patent applies preliminary anti-action by preemptively preventing the data loss condition before it can occur. The memory system deliberately selects a second row for refresh that is greater than a threshold distance away from the first row being accessed, ensuring that the refresh operation does not interfere with the host-initiated access operation. This preventive measure eliminates the risk of data loss while maintaining operational simplicity
Data Source
AI summary
Methods, systems, and devices for concurrent row refresh and activate are described. Refreshing operations for memory cells may be performed concurrently with host-initiated access operations within a same bank of a memory system. For example, the memory system may receive a command to access a first row of a bank. The memory system may select a second row of the bank to refresh based on the second row being greater than a threshold distance away from the first row. The memory system may activate both the first row and the second row concurrently, thus performing a host-initiated access operation (on the first row) and a refresh operation (on the second row) concurrently. By doing so, the system may reduce a latency for host-initiated access operations while improving the reliability of the data.