Nonvolatile Memory Read Parameter Adjustment via History Voting
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Solution Overview
Problem
As semiconductor storage devices are scaled down for higher integration and capacity, they face reliability issues due to data loss during read operations, necessitating an improvement in data retrieval methods to enhance storage device reliability.
Innovation Solution
An operating method for a storage device with a nonvolatile memory and memory controller that adjusts read parameters based on collected read histories, using first and second read parameters to optimize read voltages and reduce errors, with a voting unit updating parameters based on majority and minority histories to improve read accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If read operations are performed with fixed read parameters in scaled-down storage devices, then device complexity is reduced, but read error probability increases due to data loss
Solution Approach 1:
The patent implements a feedback mechanism where read histories are collected from previous read operations and used to adjust read parameters for subsequent operations. The memory controller monitors read results and modifies read voltages and offsets based on accumulated historical data, creating a closed-loop system that improves read accuracy while managing complexity through automated adaptation.
Solution Approach 2:
The patent dynamically changes read parameters including read voltages and read offsets based on collected read histories. Different read histories (first read histories and second read histories) are used to adjust different sets of read parameters, allowing the system to adapt to varying memory cell conditions without requiring complete redesign of the read mechanism.
2Reliability
If multiple read parameters are adjusted based on read histories, then read error probability decreases, but the complexity of parameter management increases
Solution Approach 1:
The patent segments read histories into different categories (first read histories and second read histories) and applies different adjustment strategies to different sets of read parameters. This segmentation allows the system to manage complexity by treating different parameter groups independently while still achieving overall improved read accuracy through coordinated adjustment.
3Measurement precision
If read voltages are adjusted dynamically, then read accuracy improves, but the time required for read operations increases
Solution Approach 1:
The patent performs preliminary adjustments to read parameters based on pre-collected read histories before actual read operations. By preparing and storing optimal read parameters in advance through historical analysis, the system reduces the time required during actual read operations, as the adjustments are based on pre-computed values rather than real-time calculations.
Data Source
AI summary
An operating method of a storage device includes reading data from a nonvolatile memory using first read parameters and second read parameters and collecting read histories associated with a plurality of read operations. First histories and second histories are determined from the collected read histories. The second read parameters are adjusted according to the first histories, and the first read parameters are adjusted according to the second histories. The read histories include information on read voltages used to perform the read operations, and the first histories and the second histories are determined from the collected read histories according to the number of read voltages having the same level.