Automated Voltage Demarcation Adjustment for Memory Drift
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Solution Overview
Problem
Existing memory systems face challenges in accurately reading data due to threshold voltage drift in non-volatile memory devices, which can lead to incorrect interpretations of data stored in memory cells.
Innovation Solution
The implementation of an automated voltage demarcation adjustment mechanism in a memory sub-system, where the memory sub-system controller can select an optimal demarcation voltage (VDM) without relying on host system commands, based on elapsed time since the last write operation and threshold criteria, to compensate for voltage threshold drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple commands with different VDMs are used to read data, then data accuracy is improved, but read latency increases
Solution Approach 1:
The memory sub-system controller performs preliminary actions by automatically selecting and applying the optimal VDM value before executing read commands. The controller determines the appropriate VDM based on elapsed time since the last write operation and uses this pre-determined voltage to execute read commands, eliminating the need for multiple sequential read attempts with different VDM values.
Solution Approach 2:
The memory sub-system controller performs self-service by autonomously determining and applying the optimal VDM without requiring host system intervention. The controller monitors elapsed time since the last write operation and automatically selects the appropriate VDM value, making the system self-sufficient in managing voltage demarcation adjustments.
2Device complexity
If a fixed VDM is used for all read operations, then device complexity is reduced, but drift mitigation capability deteriorates
Solution Approach 1:
The system transitions from a static, fixed VDM approach to a dynamic VDM selection mechanism. The memory sub-system controller adjusts the VDM value based on the elapsed time since the last write operation, allowing the system to adapt to changing threshold voltage conditions while maintaining simple control logic through time-based decision making.
Solution Approach 2:
The invention changes the parameter of VDM value dynamically based on operational conditions. Specifically, the controller modifies the VDM parameter according to the elapsed time since the last write operation, enabling the system to compensate for threshold voltage drift without requiring complex control mechanisms.
3Measurement precision
If VDM is adjusted frequently to compensate for threshold voltage drift, then data accuracy is improved, but wear on memory cells increases
Solution Approach 1:
The controller performs preliminary determination of the optimal VDM value based on elapsed time before executing read operations. This pre-calculated VDM selection avoids the need for frequent adjustments during operation, reducing mechanical stress on the memory cells while maintaining accurate data reading.
Solution Approach 2:
The system uses feedback from the elapsed time measurement to determine the appropriate VDM value. By continuously monitoring the time since the last write operation and using this feedback to select the optimal VDM, the system achieves accurate data reading without requiring excessive voltage adjustments that would harm memory cell longevity.
Data Source
AI summary
A memory system includes a memory device and a processing device coupled to the memory device. The processing device receives a plurality of codewords; selects a first read voltage associated with the one or more codewords, such that the first read voltage is based on a time elapsed since a last write operation with respect to a management unit comprising the one or more codewords; and applies the first read voltage to a set of memory cells storing the one or more codewords.