Controller Read Retry with Bias Voltage Grouping for Memory Accuracy
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Solution Overview
Problem
Data storage devices face challenges in accurately reading data from memory cells due to distorted threshold voltage distributions caused by interference and wear cycles, leading to errors that conventional error correction methods struggle to handle.
Innovation Solution
A data storage device with a controller that classifies memory regions into multiple groups corresponding to read bias voltage groups, performs initial read retry operations based on the primary group, and iteratively selects alternative read bias voltage groups for additional retries based on error estimation indexes to enhance data retrieval success.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional error correction methods are used to read data from memory cells, then the reading process is simple and fast, but the accuracy deteriorates due to distorted threshold voltage distributions caused by interference and wear cycles
Solution Approach 1:
The patent segments the read operation into multiple stages: initial read attempt, error detection, error estimation index calculation, and conditional read retry with adjusted read bias voltage. This segmentation allows the system to apply complex error correction only when necessary, maintaining accuracy while managing operational complexity.
Solution Approach 2:
The patent performs preliminary error estimation and calculates error estimation indexes before executing read retry operations. This preliminary action enables the system to predict potential reading errors based on distorted threshold voltage distributions and proactively adjust read bias voltage settings, improving data reading accuracy without immediately invoking complex retry mechanisms.
2Reliability
If read retry operations are performed multiple times with different read bias voltage groups, then the probability of successful data retrieval increases, but the time consumption and operational complexity increase
Solution Approach 1:
The patent implements a conditional read retry mechanism where the system performs read retry operations with adjusted read bias voltage groups only when error estimation indexes indicate potential reading errors. This partial action approach avoids unnecessary repeated read operations, reducing time consumption while maintaining high data retrieval success probability for cases that actually require retry.
Solution Approach 2:
The patent employs feedback through error estimation indexes that are calculated based on the results of initial read operations. This feedback mechanism allows the system to dynamically adjust read bias voltage settings for retry operations, improving the likelihood of successful data retrieval while minimizing the number of retry attempts needed by using information from the initial read to guide subsequent attempts.
3Productivity
If the memory device operates with high wear cycles, then the memory device has been extensively used and stored more data, but the threshold voltage distribution becomes more distorted making accurate reading difficult
Solution Approach 1:
The patent changes the read bias voltage parameter dynamically based on wear cycle indicators and error estimation indexes. As the memory device accumulates wear cycles and threshold voltage distributions become more distorted, the system adjusts the read bias voltage to compensate for these changes, maintaining measurement precision despite extensive use and high data storage capacity utilization.
Data Source
AI summary
A data storage device includes a memory device including memory regions classified into a plurality of memory groups each corresponding to a plurality read bias voltage groups; and a controller suitable for: performing for a target memory region a read retry operation based on a first read bias voltage group corresponding to a memory group in which the target memory region is included, and performing an additional read retry operation based on at least one of remaining read bias voltage groups excluding the first read bias voltage group among the plurality of read bias voltage groups, according to a result of the read retry operation.