Memory Device Threshold Voltage Distribution Shift Compensation
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Solution Overview
Problem
Memory devices face challenges in compensating for shifted threshold voltage distributions during sensing and data output operations, leading to potential read failures and reduced performance.
Innovation Solution
A memory device with a threshold voltage distribution measurement component, a distribution shift compensation table generator, and a read operation controller that measures and compensates for shifts in threshold voltage distributions by generating a distribution shift compensation table based on comparisons between first and second read operations, allowing for improved read operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the memory device performs read operations to sense data from programmed memory cells, then data can be retrieved, but the threshold voltage distribution shifts causing read failures and reduced performance
Solution Approach 1:
The patent performs a first read operation before the actual data output to measure the threshold voltage distribution in advance. Based on this measurement, a distribution shift compensation table is generated that predicts and compensates for expected shifts during subsequent read operations, thereby maintaining read reliability despite voltage distribution changes
Solution Approach 2:
The patent implements a feedback mechanism where the threshold voltage distribution measured from the first read operation is used to generate compensation values. These compensation values are then applied to adjust the read operation parameters, creating a closed-loop system that continuously adapts to voltage shifts and maintains accurate data retrieval
2Measurement precision
If the memory device compensates for threshold voltage distribution shifts using a distribution shift compensation table, then read operation accuracy improves, but device complexity increases
Solution Approach 1:
The patent divides the read operation into distinct segments: a first read operation for measurement, a compensation table generation step, and a second read operation for data output. This segmentation allows the complex compensation function to be isolated and managed separately, reducing overall device complexity while maintaining measurement precision
Solution Approach 2:
The distribution shift compensation table acts as an intermediary data structure that stores pre-calculated compensation values. This table serves as a mediator between the threshold voltage measurement and the actual read operation, simplifying the control logic by replacing complex real-time calculations with table lookups and adjustments
Data Source
AI summary
A memory device including a plurality of memory cells, a threshold voltage distribution measurement component configured to measure a threshold voltage distribution of a first read operation of sensing data from programmed memory cells among the plurality of memory cells, and a threshold voltage distribution of a second read operation of sensing the data from the programmed memory cells and outputting the data to an outside, a distribution shift compensation table generator configured to calculate a shift direction and a shift distance based on a result of comparing the threshold voltage distribution of the first read operation and the threshold voltage distribution of the second read operation, and generate a distribution shift compensation table based on the shift direction and the shift distance, and a read operation controller configured to perform a third read operation on target memory cells based on the distribution shift compensation table.