Memory Cell Voltage Sweep Using Delta Transition Storage
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Solution Overview
Problem
Memory systems face challenges in accurately identifying threshold voltages of memory cells while minimizing data storage requirements, as current methods either consume excessive memory resources or provide inaccurate representations of cell failures.
Innovation Solution
The memory system controller performs a voltage sweep operation by applying incremental voltages to memory cells, storing delta values representing logic state transitions, and compressing these values using bit shifting to reduce data storage while maintaining accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage sweep operation stores complete transition data for each memory cell, then measurement precision of threshold voltages is improved, but quantity of substance (data storage requirements) increases
Solution Approach 1:
The patent extracts only the essential information needed for threshold voltage identification by storing delta values (differences in transition counts between consecutive voltage iterations) rather than complete transition data. This extraction approach maintains measurement precision while significantly reducing data storage requirements.
Solution Approach 2:
The patent changes the parameter representation from absolute transition counts to delta values (differences between consecutive iterations). This parameter transformation allows the system to capture threshold voltage information with reduced data storage, as the delta values contain only the necessary changes rather than complete state information.
2Quantity of substance
If delta values are compressed using bit shifting, then quantity of substance (data storage) is reduced, but manufacturing precision of threshold voltage representation may worsen
Solution Approach 1:
The patent applies partial compression through bit shifting operations that retain sufficient precision for threshold voltage identification. Rather than compressing all data equally, the system applies compression selectively while maintaining adequate resolution for detecting threshold transitions, achieving a balance between storage reduction and accuracy preservation.
Data Source
AI summary
Methods, systems, and devices for methods for performing voltage sweep operations are described. Based on detecting a failure at a portion of a memory device, the memory system controller may initialize a voltage sweep operation to identify threshold voltages of the memory cells at the portion of the memory device. In one example, the memory system controller may identify and store a value (e.g., a delta value) that represents a difference between a quantity of transitions experienced by a first memory cell at a first voltage iteration and a quantity of transitions experienced by the first memory cell at a second voltage iteration. In another example, the memory system controller may identify the quantity of transitions from a first logic state to a second logic state and a quantity of transitions from the second logic state to a first logic state and store such values in respective memory arrays.