Non-volatile Memory Read Threshold Adjustment via Displacement Value
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Data storage devices face challenges in accurately reading data due to shifting threshold voltage distributions in nonvolatile memory cells, leading to errors during read operations, as existing methods struggle to adjust read voltages effectively between overlapping distributions.
Innovation Solution
A data storage device method that determines a displacement value based on section memory cell numbers and adjusts reliability values for threshold voltage sections to perform error correction, using both hard and soft decision read voltages to minimize error bits and optimize read performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional fixed read voltage is used, then device complexity is low, but read accuracy deteriorates due to threshold voltage distribution shifts
Solution Approach 1:
The system performs preliminary actions by calculating displacement values and adjusting reliability values before actual data reading occurs. The controller pre-determines the displacement value based on reference information and uses this to adjust reliability values for different threshold voltage sections, enabling the error correction system to compensate for threshold voltage shifts without requiring complex real-time voltage adjustment.
Solution Approach 2:
The invention changes the parameter of reliability values associated with different threshold voltage sections based on displacement values. By adjusting these reliability parameters, the system adapts to threshold voltage distribution shifts and improves read accuracy. The controller modifies reliability values dynamically based on calculated displacement, allowing the same hardware to maintain high accuracy under varying conditions.
2Measurement precision
If read voltage is adjusted to compensate for threshold voltage shifts, then read accuracy improves, but error correction performance deteriorates due to increased error bits
Solution Approach 1:
The system applies local quality by assigning different reliability values to different threshold voltage sections based on their specific displacement characteristics. Instead of using a uniform reliability value for all memory cells, the controller determines section-specific reliability values according to the displacement value of each section. This localized approach allows the error correction system to optimize performance for each voltage section individually, maintaining high reliability even when read voltage adjustment is needed.
3Measurement precision
If multiple read voltages are used to handle threshold voltage distributions, then read accuracy improves, but device complexity increases
Solution Approach 1:
The invention segments the threshold voltage distribution into multiple sections, with each section having its own reliability value. The controller divides the voltage range into different sections and calculates displacement values for each section independently. This segmentation allows the system to handle multiple threshold voltage distributions more effectively while managing complexity through systematic organization of the segments and their corresponding reliability parameters.
Data Source
AI summary
An operating method for a data storage device may include: determining a displacement value based on section memory cell numbers regarding a plurality of threshold voltage sections divided by a first read voltage and second read voltages; determining an adjustment direction based on the displacement value; adjusting at least one reliability value corresponding to at least one threshold voltage section among the threshold voltage sections, positioned in the adjustment direction from the first read voltage; and performing an error correction operation on data read from memory cells based on the first read voltage, using reliability values corresponding to the threshold voltage sections.