Memory Read Voltage Recovery After Power-Off Retention Drift
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Solution Overview
Problem
Current memory systems face challenges in maintaining data integrity and efficiency, particularly in managing threshold voltage distributions and read operations after idle periods or power-off conditions, which affect the Quality of Service (QoS) requirements.
Innovation Solution
The solution involves determining equivalent retention and power-off durations based on threshold voltage distributions to adjust read voltages, using a controller to manage memory operations and update read voltages according to the state information of memory cells, and implementing a system that re-determines read voltages after power-off to ensure accurate data retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read voltages are not adjusted after power-off conditions, then device complexity is reduced, but data integrity and QoS deteriorate
Solution Approach 1:
The system performs preliminary actions by determining equivalent retention duration and updating read voltages before actual read operations occur after power-off. The controller proactively adjusts read voltages based on threshold voltage distribution changes that occur during idle periods, ensuring data integrity is maintained without requiring complex real-time adjustments during operation.
Solution Approach 2:
The system implements feedback mechanisms by monitoring threshold voltage distributions of memory cells and using this information to dynamically update read voltages. The controller continuously assesses the state of memory cells and adjusts read voltages accordingly, creating a closed-loop system that maintains data integrity while adapting to changing conditions after power-off.
2Measurement precision
If read voltages are dynamically adjusted based on memory cell states, then data retrieval accuracy improves, but operation time increases
Solution Approach 1:
The system performs voltage adjustments as a preliminary action during the power-on sequence, before actual data retrieval operations begin. By determining equivalent retention duration and updating read voltages in advance, the system ensures accurate data retrieval without adding time delays to the actual read operations.
Solution Approach 2:
The system changes the parameter of read voltage dynamically based on the equivalent retention duration and threshold voltage distribution. By adjusting this critical parameter according to measured conditions, the system achieves high data retrieval accuracy while keeping the adjustment process efficient through direct parameter modification rather than complex iterative searches.
3Reliability
If equivalent retention duration is determined through threshold voltage distribution analysis, then QoS is maintained, but device complexity increases
Solution Approach 1:
The system uses feedback from threshold voltage distribution measurements to determine equivalent retention duration. By continuously monitoring the threshold voltage distributions of memory cells and using this feedback to update read voltages, the system maintains QoS requirements while using a relatively simple determination process that leverages existing memory cell characteristics.
Solution Approach 2:
The system performs self-service by using the inherent threshold voltage distributions of the memory cells themselves as the measurement basis for determining equivalent retention duration. Rather than requiring external complex measurement equipment, the system leverages the natural electrical characteristics of the memory cells to assess their state and adjust operations accordingly.
Data Source
AI summary
Examples of the present disclosure provide a memory system and an operation method thereof, and a computer readable storage medium. The memory system includes a memory and a controller coupled to the memory, and the memory includes a plurality of memory blocks. The operation method includes: writing dummy data to a selected memory block after external power off and before the memory system being powered off; and reading the dummy data in the selected memory block when the memory system is powered on again after being powered off, and determining an equivalent power-off duration of the memory system according to a read result and a preset mapping table.