Dynamic Read Voltage Adjustment for Memory Cell Data Retrieval
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Solution Overview
Problem
Existing electronic devices face challenges in accurately determining and adjusting read voltages for memory cells with multiple threshold voltage distributions, leading to potential errors in data retrieval due to the difficulty in precisely positioning the read voltage in the valley between these distributions.
Innovation Solution
A method involving a controller and non-transitory computer-readable storage medium that calculates average threshold voltages, sets a temporary read voltage, generates a reference value, calculates an error rate, and adjusts the read voltage by applying an offset value to improve data retrieval accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed read voltage is used for memory cells with multiple threshold voltage distributions, then the device complexity is reduced, but the measurement precision of threshold voltage positioning deteriorates
Solution Approach 1:
The read voltage is transformed from a fixed value to a dynamic, adjustable parameter. The system automatically calculates optimal read voltages based on threshold voltage distributions and adjusts the read voltage accordingly, enabling the system to adapt to different memory cell states and improve positioning precision without manual intervention
Solution Approach 2:
The system implements a feedback mechanism where read voltages are calculated based on threshold voltage distributions, applied to memory cells, and the results are used to refine subsequent read operations. This closed-loop approach ensures accurate positioning while maintaining automated operation
2Measurement precision
If the read voltage is manually adjusted for each threshold voltage distribution, then the measurement precision is improved, but the ease of operation deteriorates
Solution Approach 1:
The system performs self-adjustment by automatically calculating optimal read voltages based on its own threshold voltage distributions. The controller autonomously determines the appropriate read voltage without requiring external manual adjustment, thereby maintaining high precision while simplifying operation
Solution Approach 2:
The system dynamically changes the read voltage parameter based on calculated threshold voltage distributions. By automatically adjusting this critical parameter, the system achieves precise positioning without requiring user intervention, resolving the contradiction between precision and ease of operation
3Ease of operation
If the read voltage is positioned far from the valley between threshold voltage distributions, then the ease of operation is improved, but the reliability of data retrieval deteriorates
Solution Approach 1:
The manual mechanical adjustment of read voltage is replaced with an automated calculation system that uses threshold voltage distribution data to determine optimal read voltages. This substitution maintains operational simplicity while ensuring the read voltage is precisely positioned for reliable data retrieval
4Measurement precision
If multiple read voltages are calculated and applied for different threshold voltage distributions, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The system segments the threshold voltage distributions into distinct groups and calculates appropriate read voltages for each segment. This segmentation approach enables precise differentiation between distributions while managing complexity through systematic organization of the calculation process
Data Source
AI summary
An electronic device includes a controller, a non-transitory computer-readable storage medium including memory cells having a plurality of threshold voltage distributions and storing operation codes executable by the controller. Based on the operation codes, controller is configured to: calculate average threshold voltages of the plurality of threshold voltage distributions and set a temporary read voltage corresponding to average threshold voltages of adjacent threshold voltage distributions among the plurality of threshold voltage distributions; generate a reference value by reading read values of the memory cells with the temporary read voltage and decide a standard value corresponding to the temporary read voltage; calculate an error rate based on the reference value and the standard value and set an offset value by reflecting the error rate in a difference between the average threshold voltages of the adjacent threshold voltage distributions; and set a read voltage by applying the offset value to the temporary read voltage.