Memory Read Offset Voltage Bins for Charge Loss Adaptation
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Solution Overview
Problem
Existing memory systems face inefficiencies in managing read operations due to static assignment of offset voltages, leading to excessive read errors and resource wastage, as they fail to adapt to changes in storage charge loss (SCL) over time and temperature variations.
Innovation Solution
A memory sub-system dynamically adjusts offset voltages based on SCL and temperature, using a controller to reassign memory blocks to bins with appropriate offset voltage sets, transitioning from coarse to fine granularity as needed to improve read accuracy and reduce errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If static assignment of offset voltages is used, then device complexity is reduced, but read accuracy deteriorates due to inability to adapt to storage charge loss and temperature variations
Solution Approach 1:
The patent implements dynamic adjustment of offset voltages by the controller based on detected storage charge loss and temperature conditions. The controller transitions from static to dynamic voltage assignment, allowing read accuracy to adapt to changing memory cell states while managing complexity through systematic control algorithms.
Solution Approach 2:
The controller changes the offset voltage parameters dynamically based on detected storage charge loss and temperature. By adjusting voltage levels according to environmental and temporal conditions, the system maintains high read accuracy without requiring complete system redesign.
2Measurement precision
If coarse granularity offset voltage bins are used, then device complexity is reduced, but read accuracy deteriorates due to insufficient resolution for fine-tuning read voltages
Solution Approach 1:
The patent segments offset voltage bins into coarse and fine granularity levels. Coarse bins provide broad coverage for initial read operations, while fine bins enable precise voltage adjustment when needed. This hierarchical segmentation allows the system to achieve high precision without managing all fine bins continuously, reducing overall complexity.
Solution Approach 2:
The system applies fine granularity bins only partially - specifically when read errors are detected or when high precision is required. For normal operations, coarse bins suffice, reducing the effective complexity of bin management while maintaining the capability for high precision when needed.
3Reliability
If dynamic adjustment of offset voltages is implemented, then read accuracy is improved, but resource consumption increases due to continuous monitoring and adjustment operations
Solution Approach 1:
The controller performs dynamic adjustment of offset voltages periodically or event-driven rather than continuously. By monitoring storage charge loss and temperature at specific intervals or upon detecting errors, the system maintains high read reliability while minimizing the energy consumption associated with constant monitoring and adjustment operations.
Solution Approach 2:
The system uses error detection mechanisms to trigger voltage adjustments only when necessary. The memory subsystem essentially self-regulates by detecting read failures and automatically adjusting offset voltages to correct them, rather than requiring continuous external intervention, thus improving reliability efficiently.
4Adaptability or versatility
If fixed number of bins is used, then device complexity is reduced, but adaptability deteriorates when storage charge loss exceeds initial calibration range
Solution Approach 1:
The patent implements dynamic bin assignment where the controller can allocate and reassign bins based on detected storage charge loss levels. This dynamic approach allows the system to adapt to varying degrees of charge loss over time and across different memory blocks, improving versatility while managing complexity through systematic allocation strategies.
Solution Approach 2:
The controller applies different bin configurations to different memory blocks based on their specific charge loss characteristics. By tailoring bin assignments locally to each block's needs rather than using a uniform configuration, the system achieves high adaptability while managing complexity through localized optimization.
Data Source
AI summary
A memory device to manage the assignment of offset voltages for read operations, and to adjust read voltages using the offset voltages. The offset voltages are dynamically adjusted by a controller during operation of the memory device in response to read errors. In one approach, a first bin of offset voltages is assigned to a first region of a storage media. The first offset voltages are used to adjust read voltages for reading a page of first memory cells in the first region. The controller determines that at least one error has occurred in reading the page. In response to determining the error, the controller determines second offset voltages that can be used to read the first memory cell without causing a read error. Based on the second offset voltages, the controller identifies third offset voltages for assigning to the first region. The third offset voltages are used for adjusting read voltages for subsequent reads of pages in the first region. The third offset voltages can be assigned from an existing offset voltage bin, or a new offset voltage bin can be generated for the assignment.