Flash Memory Page-Group Threshold Tuning for Accurate Data Reads
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Solution Overview
Problem
Existing flash memory systems face challenges in accurately reading data due to error bits caused by floating voltage disturbances, especially in multi-level cell flash memories, where the error checking and correcting (ECC) circuit can only correct a limited number of errors, leading to incorrect data reading as the number of error bits increases with advancements in fabrication and storage density.
Innovation Solution
A data reading method that groups physical pages into page groups, configures threshold voltage sets for each group, and adjusts these voltages based on error bit information from adjacent pages to correct data that cannot be corrected by the ECC circuit, ensuring accurate data retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of data bits stored in each memory cell is increased to improve storage density, then storage capacity is improved, but the number of error bits increases
Solution Approach 1:
The patent segments physical pages into multiple page groups (first page group, second page group, etc.), with each group having dedicated threshold voltage sets. This segmentation allows independent optimization and adjustment of reading parameters for different page groups, enabling more precise error correction in high-density storage regions while maintaining overall storage capacity.
Solution Approach 2:
The patent dynamically adjusts threshold voltages based on error bit information detected from adjacent pages. When error bits are detected in a first physical page, the system modifies the threshold voltage set for the corresponding page group and retries reading. This parameter adjustment compensates for voltage disturbances and reduces error bits without sacrificing storage density.
2Measurement precision
If threshold voltage adjustment is performed to correct uncorrectable errors, then data reading accuracy is improved, but reading time and complexity increase
Solution Approach 1:
The patent performs preliminary error detection by comparing read data with ECC correction results. When errors are detected, the system proactively adjusts threshold voltages before attempting to read adjacent pages, preventing propagation of reading errors and reducing the need for multiple retry cycles, thus optimizing reading time.
Solution Approach 2:
The system implements a feedback mechanism where error bit information from read operations is used to dynamically adjust threshold voltage sets for subsequent readings. The controller monitors error rates and automatically modifies reading parameters, creating a closed-loop system that improves accuracy while minimizing unnecessary reading retries and time loss.
Data Source
AI summary
A data reading method for a rewritable non-volatile memory module is provided, wherein the rewritable non-volatile memory module has a plurality of physical pages. The data reading method includes grouping the physical pages into a plurality of physical page groups and configuring a corresponding threshold voltage set for each of the physical page groups. The data reading method also includes respectively reading data from the physical pages of the physical page groups by using the corresponding threshold voltage sets. The data reading method further includes when data read from one of the physical pages of one of the physical page groups cannot be corrected by using an error checking and correcting (ECC) circuit, updating the threshold voltage set corresponding to the physical page group.