Memory Controller Lookup Table for Read Voltage Optimization
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Solution Overview
Problem
In rewritable non-volatile memory modules, the optimal read voltages for different physical programming units often differ, leading to varying error bit counts when using a single read voltage group, which reduces the success rate of decoding operations.
Innovation Solution
A decoding method and memory controlling circuit unit that record optimal read voltages for each physical programming unit group in a lookup table, allowing for the selection of the best voltages to minimize error bit counts during decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single read voltage group is used for reading all physical programming units, then the device complexity is reduced, but the error bit count increases due to suboptimal reading conditions for different physical programming units
Solution Approach 1:
The system performs preliminary reading operations using multiple read voltage groups before the actual decoding process. By pre-reading data with different voltage groups and evaluating error bit counts, the system identifies the optimal read voltage group for each physical programming unit in advance, storing these optimal voltage groups in a lookup table for subsequent decoding operations.
Solution Approach 2:
The system changes the read voltage parameter by selecting from multiple predetermined read voltage groups (first read voltage group, second read voltage group, etc.) with different voltage levels. By adjusting the voltage parameter based on the physical programming unit type (upper, lower, or center), the system optimizes the reading condition to minimize error bit counts and improve decoding success rate.
2Reliability
If optimal read voltages are determined for each physical programming unit, then the error bit count is minimized, but the device complexity increases due to multiple read voltage groups and lookup table management
Solution Approach 1:
The system creates a lookup table that stores copies of optimal read voltage group information for different physical programming units. Instead of performing complex real-time analysis during decoding, the system uses pre-determined voltage group selections stored in the lookup table, simplifying the actual decoding process while maintaining high reliability.
Solution Approach 2:
The system performs preliminary testing and evaluation to determine optimal read voltage groups for each physical programming unit before actual decoding operations. This preliminary action includes reading test data with different voltage groups, calculating error bit counts, and storing the results in a lookup table, thereby avoiding complex real-time decisions during production decoding.
3Measurement precision
If multiple read voltage groups are used for different physical programming units, then the measurement precision of data reading is improved, but the loss of time increases due to additional reading operations
Solution Approach 1:
The system performs optimal read voltage group determination in advance during initialization or idle periods, storing the results in a lookup table. During actual decoding operations, the system simply retrieves the pre-determined optimal voltage group from the lookup table based on the physical programming unit identifier, avoiding time-consuming real-time voltage selection while maintaining high reading accuracy.
Solution Approach 2:
The system automatically determines and stores optimal read voltage groups for each physical programming unit without requiring manual intervention or complex real-time analysis. The lookup table serves as a self-service mechanism that provides quick access to optimal voltage information during decoding operations, reducing time loss while maintaining measurement precision.
Data Source
AI summary
A decoding method, a memory controlling circuit unit, and a memory storage device are provided. The method includes: when first data is read from a first upper physical programming unit of a first physical programming unit group by using a second voltage selected from a first read voltage group, and a first error bit count of the first data is not greater than a first error bit count threshold, recording the second voltage; when a second data is read from a first lower physical programming unit of a second physical programming unit group by using a fourth voltage selected from a second read voltage group, and a second error bit count of the second data is not greater than a second error bit count threshold, recording the fourth voltage; generating a lookup table according to the second voltage and the fourth voltage; and performing a decoding operation according to the lookup table.