Time-Interleaved Page Buffer Read for Threshold Voltage Shifts
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Solution Overview
Problem
Non-volatile memory devices face deterioration issues due to shifting threshold voltage distributions, necessitating dynamic adjustment of operation conditions to maintain data readability, which existing techniques fail to address effectively.
Innovation Solution
Implementing a time interleaved sampling page buffer that performs a two-step Even Odd Sensing (EOS) read operation to dynamically adjust read levels and timing based on the shifting threshold voltages, ensuring accurate data retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If initial read levels are used for data retrieval, then the read operation is simple and fast, but data retrieval accuracy deteriorates due to voltage shifts from memory deterioration
Solution Approach 1:
The patent implements dynamic read level adjustment by performing multiple sensing operations at different read levels and selecting the optimal read level based on sensing results. This dynamic adaptation allows the system to compensate for voltage shifts caused by memory deterioration, thereby maintaining data retrieval accuracy without requiring complex external calibration equipment.
Solution Approach 2:
The patent employs feedback mechanisms where sensing operations are performed to detect threshold voltage shifts, and the detected information is used to adjust subsequent read levels. This closed-loop feedback system automatically adapts to memory deterioration, resolving the contradiction between maintaining accuracy and avoiding complex external adjustment mechanisms.
2Measurement precision
If multiple sensing operations are performed to detect voltage shifts, then data retrieval accuracy is maintained, but read operation time increases
Solution Approach 1:
The patent segments the read operation into multiple distinct sensing steps, each targeting specific voltage shift detection. By dividing the overall read operation into manageable segments (first sensing operation, second sensing operation, main read operation), the system can efficiently detect voltage shifts without requiring excessive time, as each segment performs a specific function rather than redundant full-spectrum sensing.
Solution Approach 2:
The patent performs sensing operations at selected read levels rather than exhaustive sensing at all possible levels. This partial action approach detects sufficient voltage shift information to maintain accuracy while avoiding the time penalty of complete exhaustive sensing, thereby balancing precision requirements with time constraints.
3Reliability
If read levels are dynamically adjusted to compensate for deterioration, then data integrity is maintained, but operation conditions become more complex to manage
Solution Approach 1:
The patent implements self-service mechanisms where the memory device automatically performs sensing operations to detect its own voltage shifts and adjusts its own read levels without external intervention. This self-diagnosis and self-adjustment capability maintains data integrity while simplifying operation management, as the system manages its own deterioration compensation without requiring complex external control.
Solution Approach 2:
The patent dynamically changes read level parameters based on detected voltage shifts. By automatically adjusting these parameters in response to memory deterioration, the system maintains data integrity while the parameter adjustment process is managed internally through standardized sensing and adjustment procedures, preventing operation complexity from escalating.
4Quantity of substance
If the number of memory cells and word lines increases to expand storage capacity, then storage capacity increases, but threshold voltage distribution shifts more significantly due to deterioration
Solution Approach 1:
The patent applies local quality adjustments by performing sensing operations on selected memory cells and word lines to detect local voltage shifts. Rather than applying uniform read levels across the entire memory array, the system identifies and compensates for local variations in threshold voltage distributions, thereby maintaining stability in high-capacity memory structures where deterioration effects can vary across different regions.
Data Source
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AI summary
Provided is a storage device that performs a read operation by using a time interleaved sampling page buffer. The storage device controls a sensing point in time, when bit lines of even page buffer circuits are sensed, and a sensing point in time, when bit lines of odd page buffer circuits are sensed, with a certain time difference, and performs an Even Odd Sensing (EOS) operation in a stated order of even sensing and odd sensing. The storage device performs a two-step EOS operation and performs a main sensing operation on a selected memory cell according to a result of the two-step EOS operation.