Nonvolatile Memory Read Voltage Determination via Dynamic Defense Code Selection
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Solution Overview
Problem
The existing methods for determining the optimum read voltage in nonvolatile memory systems are time-consuming as they require using all defense codes in a specific order, leading to reduced performance due to the gradual variation in threshold voltage distribution of memory cells.
Innovation Solution
A method that selects a subset of defense codes based on read voltage level determination information and read environment information to determine the optimal read voltage level, allowing for a more efficient read operation by using only the necessary codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all defense codes are used in a given order to determine the optimum read voltage, then the read voltage determination is comprehensive and accurate, but the read operation time is extended and system performance is reduced
Solution Approach 1:
The patent segments the complete set of defense codes into multiple groups, where each group contains a subset of defense codes. By selecting and executing only one group based on read environment information, the system divides the comprehensive verification process into manageable segments, reducing the number of codes that need to be executed while maintaining adequate read voltage determination accuracy.
Solution Approach 2:
The patent applies partial action by executing only a portion of the available defense codes rather than all of them. Based on read environment information (such as temperature, retention time, and program/erase cycle count), the system selectively executes a sufficient subset of defense codes that provides adequate read voltage determination without the overhead of running the complete set, thereby reducing read operation time while maintaining acceptable accuracy.
2Reliability
If multiple defense codes are executed to determine the optimal read voltage level, then the read voltage determination is thorough, but the read operation speed is reduced
Solution Approach 1:
The patent implements dynamic defense code selection by adjusting which defense codes are executed based on real-time read environment information. The system dynamically adapts the defense code execution strategy according to factors such as temperature, retention time, and program/erase cycle count, executing only the necessary subset of codes required for reliable read voltage determination under current conditions, thereby maintaining reliability while improving read operation speed.
Solution Approach 2:
The patent changes the parameter of defense code execution quantity based on read environment information. By monitoring environmental parameters and adjusting the number and type of defense codes executed accordingly, the system optimizes the balance between read voltage determination reliability and read operation speed, executing more codes when reliability is critical and fewer codes when speed is prioritized.
Data Source
AI summary
A read operation method of a nonvolatile memory includes selecting at least a first selection defence code from among a plurality of defence codes by using read voltage level determination information and read environment information, the read environment information including values respectively corresponding to a plurality of factors; determining a level of a read voltage for performing a read operation based on the first selection defence code; and performing the read operation by using the read voltage having the determined level.