Non-Volatile Memory Read Voltage Adjustment for Error Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In memory systems, inappropriate read voltage values lead to increased data errors and latency due to factors like program disturb, read disturb, and data retention, which result in inefficient error correction and retry operations.
Innovation Solution
A memory system with a controller that adjusts read voltages based on threshold level changes by storing initial and shifted voltage values, using tables to manage shift patterns and indices, reducing memory size requirements for storing read voltage information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read voltage values are not adjusted appropriately, then data reading speed is maintained, but data error rate increases and requires error correction processing
Solution Approach 1:
The system performs preliminary detection of threshold voltage shifts and adjusts read voltages before actual data reading operations. By detecting threshold changes and storing adjusted voltage values in advance, the system ensures accurate reading without requiring error correction retries, thus reducing read latency while maintaining data accuracy.
2Productivity
If detailed read voltage information is stored for all memory blocks, then read performance is improved, but memory size requirements increase
Solution Approach 1:
The system extracts and stores only the essential read voltage adjustment information (initial voltage values and shift amounts) rather than storing complete voltage profiles for all memory blocks. This selective storage approach maintains read performance by preserving critical adjustment data while significantly reducing the memory size required for storing voltage information.
3Reliability
If read voltage is adjusted frequently to compensate for threshold shifts, then data reading accuracy is improved, but system complexity increases
Solution Approach 1:
The system implements self-service by automatically detecting threshold voltage shifts and adjusting read voltages without requiring complex external control. The memory device itself monitors its threshold changes and applies appropriate voltage adjustments, simplifying the overall control architecture while maintaining high reading accuracy through adaptive voltage compensation.
Data Source
AI summary
A memory system includes non-volatile memory cells for storing multiple bit data and a controller configured to control to apply read voltages to the non-volatile memory cells at different threshold levels to read data written to the non-volatile memory cells. The non-volatile memory cells comprise different sub-groups. The controller stores first information indicating a first initial value for each of the different threshold level of the read voltages, second information that indicates whether data can be successfully read from each sub-group when the respective different threshold levels of the read voltages are set to the first initial values, and third information that indicates a second initial value for each different threshold level of the read voltages for at least one sub-group for which data reading was unsuccessful when a read voltage was set to the first initial value.