Flash Memory Threshold Voltage Update via Symbol Transition Feedback
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Solution Overview
Problem
The increasing storage density in semiconductor memory devices, such as flash memory, leads to a higher likelihood of data errors during read and write operations due to electrical fluctuations and defects, which existing error control coding engines struggle to manage effectively.
Innovation Solution
A system that utilizes symbol transition information obtained during normal memory read operations to generate updated reading threshold voltages, reducing the burden on error correction engines and enhancing data reliability without introducing extraneous read operations that cause latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If storage density is increased in flash memory cells, then storage capacity is improved, but data reliability deteriorates due to higher susceptibility to electrical fluctuations and defects
Solution Approach 1:
The system implements a feedback mechanism where symbol transition information obtained during normal read operations is used to dynamically update reading threshold voltages. The memory controller continuously monitors read errors and adjusts threshold voltages accordingly, creating a closed-loop system that adapts to changing storage medium characteristics and maintains data reliability despite increased storage density
Solution Approach 2:
The system changes the reading threshold voltage parameter dynamically based on symbol transition information and program-erase cycle counts. By adjusting this critical parameter in response to observed error patterns, the system maintains optimal read accuracy across varying storage conditions without requiring additional hardware resources
2Reliability
If error control coding engines are used to correct read errors, then data reliability is improved, but processing complexity and latency increase
Solution Approach 1:
The system performs preliminary action by proactively updating reading threshold voltages based on symbol transition information before errors accumulate to uncorrectable levels. This preventive approach reduces the burden on ECC engines by addressing the root cause of read errors, thereby lowering processing complexity and latency
Solution Approach 2:
The memory controller performs self-service by automatically adjusting its own reading threshold voltages using feedback from read operations. This self-adjustment mechanism reduces reliance on complex ECC processing by maintaining optimal read conditions, thereby simplifying the overall error correction burden
3Reliability
If traditional threshold voltage adjustment methods are used, then data reliability is improved, but additional read operations are required causing latency and performance degradation
Solution Approach 1:
The system achieves multi-functionality by extracting symbol transition information during normal read operations and using this same information for threshold voltage updates. This approach serves dual purposes: maintaining data integrity through error monitoring and optimizing read performance through adaptive threshold adjustment, all within existing read operations without requiring separate calibration reads
Solution Approach 2:
The system maintains continuity of useful action by continuously updating threshold voltages using symbol transition information obtained during ongoing read operations. This continuous adaptation process occurs in the background during normal operation, eliminating the need for periodic read pauses or separate calibration sequences that would cause latency
Data Source
AI summary
The various implementations described herein include systems, methods and/or devices that may enhance the reliability with which data can be stored in and read from a memory. The method includes obtaining symbol transition information corresponding to symbol read errors identified while reading data from flash memory cells in a flash memory device. The method further includes determining a reading threshold voltage offset, based at least in part on: a plurality of probability values determined from the symbol transition information; a current count of program-erase cycles; and a word line zone value for a word line zone containing the flash memory cells. Additionally, the method includes generating an updated reading threshold voltage in accordance with the reading threshold voltage offset and the current value of the reading threshold voltage.