Memory Block Refresh on Power-Up Using Age and Temperature
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Solution Overview
Problem
Existing memory devices face issues with data retention degradation and cross-temperature effects, leading to reliability and functionality problems, particularly in NAND-based memory devices, due to unsuitable refresh operations that do not account for system parameters and environmental conditions.
Innovation Solution
The memory device is configured to detect power up and determine if a block satisfies refresh conditions based on age and temperature thresholds, allowing for selective high-priority or low-priority refresh operations to mitigate data retention degradation and cross-temperature effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refresh operations are performed on memory blocks, then data retention degradation is mitigated, but memory cell life span is reduced
Solution Approach 1:
The patent changes the parameters of refresh operations by introducing age-based and temperature-based conditions. Instead of uniform periodic refreshing, the system adjusts refresh frequency and priority based on memory block age (time since last program/erase) and temperature exposure, thereby optimizing the balance between data retention and memory cell longevity
Solution Approach 2:
The patent implements dynamic refresh strategies where refresh operations adapt to changing conditions. The refresh priority and frequency are dynamically adjusted based on real-time temperature monitoring and memory block age, transitioning from static periodic refresh to condition-based dynamic refresh
2Reliability
If refresh operations are performed frequently, then data integrity is improved, but system performance and productivity deteriorate
Solution Approach 1:
The patent applies partial refresh action by selectively refreshing only those memory blocks that meet specific age and temperature conditions, rather than refreshing all blocks uniformly. This partial approach maintains data integrity for vulnerable blocks while avoiding unnecessary refresh operations on stable blocks, thus preserving system performance
Solution Approach 2:
The patent performs preliminary assessment of memory block conditions (age and temperature) before executing refresh operations. By pre-evaluating which blocks require refreshing based on stored metadata and current conditions, the system avoids unnecessary refresh operations that would degrade performance
3Ease of operation
If refresh operations are performed without considering temperature conditions, then operational simplicity is maintained, but cross-temperature effects cause reliability issues
Solution Approach 1:
The patent implements self-service temperature monitoring and condition assessment within the memory device. Temperature sensors and condition evaluation logic are integrated into the memory controller, allowing the system to autonomously determine when refresh operations are needed based on temperature conditions, maintaining operational simplicity while improving reliability
Data Source
AI summary
In some implementations, a memory device may detect power up and may identify, based on detecting the power up, a plurality of blocks of the memory device for which a power up based refresh determination is to be performed. The memory device may perform the power up based refresh determination on the plurality of blocks. The memory device may determine whether a block, of the plurality of blocks, satisfies at least one of an age condition that is based on a difference between a current time and an opening time associated with opening the block for programming, or a temperature condition that is based on a difference between a current temperature and an opening temperature associated with the block at the opening time. The memory device may selectively refresh the block based on determining whether the block satisfies at least one of the age condition or the temperature condition.