NAND Block Read Thresholds Adjusted by Write and Read Temperature
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Solution Overview
Problem
Existing memory devices face inefficiencies due to the use of fixed read voltage thresholds, which do not account for varying optimal read voltage thresholds caused by different conditions at read and write times, leading to time-consuming read retry processes and reduced performance.
Innovation Solution
Implementing a temperature-based block read system that tracks and determines read voltage thresholds based on both the recorded write temperature and the current read temperature for non-volatile memory cells, using a controller to adjust read operations accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed read voltage threshold is used for all blocks, then the device complexity is reduced, but read reliability deteriorates due to varying temperature conditions
Solution Approach 1:
The patent implements dynamic read voltage threshold adjustment based on temperature conditions. The system transitions from a fixed voltage threshold to a dynamic one that changes according to the operating temperature of the memory blocks, thereby maintaining read reliability across varying thermal conditions without requiring excessive complexity in voltage management
Solution Approach 2:
The patent changes the read voltage threshold parameter based on temperature measurements. By monitoring temperature and adjusting the voltage threshold accordingly, the system optimizes read operations for different thermal conditions, resolving the contradiction between using a simple fixed threshold and maintaining high reliability under varying conditions
2Reliability
If read retry processes are implemented to correct data errors, then read reliability is improved, but read time increases drastically reducing productivity
Solution Approach 1:
The patent performs preliminary temperature measurement and voltage threshold determination before executing read operations. By pre-adjusting the read voltage threshold based on temperature conditions, the system reduces the likelihood of read errors and subsequent retries, thereby maintaining both high reliability and fast read speeds without the need for extensive retry processes
3Reliability
If temperature tracking and dynamic voltage adjustment are implemented, then read reliability is improved, but device complexity increases
Solution Approach 1:
The patent implements a self-service temperature management mechanism where the memory device monitors its own temperature and automatically adjusts read voltage thresholds without external intervention. This self-adjusting capability improves read reliability while minimizing the added complexity by eliminating the need for external temperature control systems
Data Source
AI summary
A solid-state memory device that performs temperature-based block reads includes an array of non-volatile memory cells and a controller. The controller is configured to track a temperature for a region of the array of non-volatile memory cells in response to data being written to the region. The controller is configured to determine a read voltage threshold for a read request for the region based on both the tracked temperature for the region and a temperature determined for the region in response to a read request. The controller is configured to perform a read operation for the region using the determined read voltage threshold.