Memory Refresh Management Using Access-Monitored RFM Flags
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Solution Overview
Problem
Existing memory devices face inefficiencies in managing refresh operations, leading to increased power consumption and time wastage due to unnecessary refresh commands, particularly when certain access patterns cause accelerated decay in nearby memory cells.
Innovation Solution
Implementing monitored refresh management (MRFM) operations by tracking access counts for word lines, setting RFM flags when thresholds are crossed, and issuing targeted refresh commands only when necessary, thereby optimizing refresh operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refresh operations are performed frequently to prevent information loss, then data reliability is improved, but power consumption increases
Solution Approach 1:
The patent changes the refresh operation parameters from fixed periodic execution to dynamic execution based on monitored access patterns. The refresh interval and target selection are adjusted according to the detected aggressor row patterns, optimizing the balance between data reliability and power consumption.
Solution Approach 2:
The patent implements a feedback mechanism where access patterns are monitored and used to dynamically control refresh operations. The system detects aggressor rows through continuous monitoring and uses this information to trigger targeted refresh operations only when necessary, creating a closed-loop control system that adapts to actual memory usage patterns.
2Reliability
If targeted refresh operations are performed to address specific aggressor rows, then refresh effectiveness is improved, but device complexity increases
Solution Approach 1:
The patent segments the memory array into multiple banks, allowing independent monitoring and refresh operations for each bank. This segmentation enables targeted refresh of specific aggressor rows without affecting other memory regions, improving refresh effectiveness while managing complexity through modular organization.
Solution Approach 2:
The patent applies local quality by implementing monitoring and refresh operations at the bank level rather than uniformly across the entire memory array. Each bank can have its own aggressor row patterns and refresh requirements, allowing customized refresh strategies for different memory regions based on their specific access patterns.
3Measurement precision
If monitoring is continuously performed to detect aggressor rows, then refresh precision is improved, but use of energy increases
Solution Approach 1:
The patent implements periodic monitoring of access patterns rather than continuous monitoring. The system checks for aggressor row patterns at scheduled intervals and triggers refresh operations based on these periodic assessments, reducing the energy required for monitoring while maintaining sufficient precision to detect meaningful access patterns.
Data Source
AI summary
A controller performs an access operation on a word line which is in a portion of a memory array in a memory device. The controller counts accesses on a portion-by-portion basis (e.g., a bank-by-bank basis, a sub-bank-by-sub-bank basis, etc.). The memory counts accesses on a word line-by-word line basis. The memory sets a refresh management (RFM) flag for a portion based on the counts associated with the word lines in that portion. The controller checks the RFM flag for a portion based on the access count for the portion. The controller issues an RFM command after checking the RFM flag if the RFM flag is set.