Memory Controller Dynamic Read Voltage Adjustment
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Solution Overview
Problem
The challenge is to improve the reliability of read data in non-volatile memory devices, particularly due to changes in threshold voltage distributions over time, which affect data integrity.
Innovation Solution
A storage device and its operating method, which include a non-volatile memory and a memory controller. The memory controller sets a search region defined by start and end read voltages and determines if this region is within a multi-peak region of the threshold voltage distribution. Based on this, it either changes the search region or determines a new read voltage to optimize data retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed read voltage is used for data retrieval, then the operation is simple and fast, but data integrity deteriorates due to threshold voltage distribution changes over time
Solution Approach 1:
The patent implements dynamic read voltage adjustment by determining optimal read voltages through valley search operations based on current threshold voltage distributions. The memory controller adapts read voltages in real-time according to measured distribution characteristics, transitioning from fixed to dynamic voltage selection to maintain data integrity despite threshold voltage shifts over time
Solution Approach 2:
The patent employs feedback mechanisms where the memory controller measures actual threshold voltage distributions from memory cells and uses this information to determine optimal read voltages. The system continuously monitors and adjusts read parameters based on measured characteristics, creating a closed-loop system that maintains reliability without requiring complex manual intervention
2Measurement precision
If the search region is fixed, then the operation is simple, but read voltage determination accuracy deteriorates when threshold voltage distribution changes
Solution Approach 1:
The patent dynamically adjusts the search region boundaries based on measured threshold voltage distribution characteristics. The memory controller modifies search region parameters (start and end voltages, step sizes) according to the actual distribution shape and spread, enabling precise read voltage determination while adapting to changes in memory cell characteristics over time
Solution Approach 2:
The patent changes multiple parameters including search region boundaries, voltage step sizes, and search depths based on measured distribution characteristics. By adjusting these parameters dynamically, the system achieves high measurement precision for read voltage determination while managing complexity through automated parameter optimization
3Reliability
If read voltage is determined without considering threshold voltage distribution, then the process is fast, but data reliability decreases due to erroneous read voltages
Solution Approach 1:
The patent performs preliminary measurements of threshold voltage distribution characteristics during idle periods or initialization phases. The memory controller pre-determines optimal read voltages based on measured distributions and stores them for use during actual data read operations, reducing the time needed during critical data retrieval while maintaining high reliability
Solution Approach 2:
The patent continuously monitors and updates threshold voltage distribution characteristics in the background during normal operation. The memory controller maintains ongoing measurements and voltage optimization processes that run concurrently with data operations, ensuring reliable read voltage determination without significant time loss during critical read operations
Data Source
AI summary
Provided are a storage device and an operating method of a memory controller. The storage device includes a non-volatile memory that outputs data from selected memory cells based on read voltage information, the read voltage information including a start read voltage, an end read voltage, and a read command. Moreover, the storage device includes a memory controller that determines whether a search region defined by the start read voltage and the end read voltage is within a multi-peak region of a threshold voltage distribution corresponding to a first state of the selected memory cells, based on the search region being within the multi-peak region, change the search region, and based on the search region not being within to the multi-peak region, determine a new read voltage using the search region.