Nonvolatile Memory Control Unit Read Voltage Adjustment
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Solution Overview
Problem
Data storage devices using nonvolatile memory devices face challenges in maintaining data reliability due to program failures, which can lead to errors and instability in data access and storage.
Innovation Solution
A data storage device with a control unit that adjusts read voltage to differentiate between erase and program states, allowing for error handling by comparing reference values and flipped bits, thereby improving data reliability in case of program failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a program operation is performed on memory cells of a page, then data is stored in the memory cells, but program failures may occur leading to data errors and reduced reliability
Solution Approach 1:
The patent applies preliminary action by performing a read operation immediately after the program operation to detect program failures. The control unit reads data from the memory cells before finalizing the storage operation, allowing early detection of program failures and enabling corrective actions such as re-programming or error logging, thus preventing corrupted data from being considered successfully stored.
Solution Approach 2:
The patent implements feedback by using the read operation results to determine whether the program operation was successful. The control unit compares the read data with expected values or checks for program fail flags, and based on this feedback, it decides whether to re-attempt the program operation, mark the page as failed, or proceed with normal operations. This closed-loop feedback mechanism continuously monitors and improves data reliability.
2Measurement precision
If read voltage is adjusted to differentiate between erase and program states, then discrimination accuracy is improved, but additional control complexity is introduced
Solution Approach 1:
The patent applies dynamics by making the read voltage adjustable and adaptive rather than fixed. The control unit dynamically selects different read voltage levels depending on the operational context - using higher read voltages to distinguish between erase and program states when needed, and adjusting voltages based on detected threshold voltage distributions. This dynamic voltage adjustment improves state discrimination accuracy while the control unit manages the complexity through algorithmic decision-making rather than hardware complexity.
Data Source
AI summary
A data storage device includes a nonvolatile memory device; and a control unit suitable for controlling a program operation for memory cells of a page of the nonvolatile memory device, and processing a program fail in the case where the program operation fails, wherein the control unit adjusts a read voltage for discriminating an erase state and a program state having a threshold voltage most adjacent to the erase state, reads out data by applying the adjusted read voltage to the memory cells of the page, and performs an error handling operation to data stored in the memory cells of the page according to a result of comparing a reference value and a number of flipped bits of the data read out by applying the varied read voltage.