Nonvolatile Memory Read Voltage Compensation via Retention Groups
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Solution Overview
Problem
Nonvolatile memory devices face read failures due to variations in threshold voltage distributions caused by factors like charge leakage and temperature changes, leading to increased read latency and degraded performance.
Innovation Solution
The method involves dividing memory blocks into retention groups, generating time-difference information and offset information to adjust read voltages, and using an artificial neural network to generate compensated read voltages, thereby improving read operation success and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed read sequence is adopted, then the read operation structure is simple, but read latency increases and performance degrades when operating conditions vary
Solution Approach 1:
The patent implements a dynamic read sequence that adapts to varying operating conditions such as temperature and erase program interval. Instead of using a fixed read sequence, the system dynamically selects and adjusts the read sequence based on real-time condition detection, thereby reducing read latency and improving performance without excessive complexity
Solution Approach 2:
The patent changes the parameters of the read operation based on detected operating conditions. By monitoring parameters like temperature and EPI, the system adjusts read voltage levels and sequence timing parameters dynamically, allowing optimal read performance under varying conditions while maintaining manageable system complexity
2Reliability
If read voltages are adjusted to compensate for threshold voltage variations, then read accuracy improves, but device complexity and control difficulty increase
Solution Approach 1:
The patent employs feedback mechanisms where the system monitors operating conditions (temperature, EPI) and uses this information to adjust read voltages dynamically. This closed-loop approach improves read accuracy by compensating for threshold voltage variations while managing complexity through condition-based control strategies
Solution Approach 2:
The system performs preliminary detection of operating conditions and pre-adjusts read voltages before actual read operations. By detecting temperature and EPI in advance and preparing appropriate voltage compensation values, the system improves read reliability without requiring complex real-time control during the read operation itself
3Reliability
If multiple read operations are performed with different sequences, then read reliability improves, but read latency and time loss increase
Solution Approach 1:
The patent implements dynamic read sequence selection that adapts to operating conditions. Instead of always performing multiple read operations with different sequences, the system dynamically determines the appropriate read sequence based on detected conditions, achieving reliable reads while minimizing unnecessary time delays
Solution Approach 2:
The system changes read operation parameters including voltage levels and sequence timing based on detected operating conditions. By adjusting these parameters dynamically, the system achieves reliable read operations with a single optimized read sequence in many cases, reducing the need for multiple retry operations and associated latency
Data Source
AI summary
A method of operating a nonvolatile memory device is provided. The method includes: dividing a memory block of a plurality of memory blocks provided in the nonvolatile memory device into a plurality of retention groups; generating time-difference information including a plurality of erase program interval (EPI) values corresponding to the plurality of retention groups; generating offset information including a plurality of offset values corresponding to differences between a plurality of default read voltages and a plurality of corrected read voltages; generating compensated read voltages corresponding to a read address based on the offset information and the time-difference information; and performing a read operation to read data from the nonvolatile memory device based on the read address and the compensated read voltages.