Memory Controller Read Voltage Adjustment for Temperature Compensation
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Solution Overview
Problem
Memory systems face inefficiencies in data processing due to temperature variations, which can lead to increased fail bits and reduced data integrity, as the default read voltage may not account for temperature-induced changes in threshold voltages.
Innovation Solution
A memory system and operating method that utilize real-time clock (RTC) and country information to adjust read voltages based on temperature data stored in tables, allowing for a second read operation with optimized voltages when fail bits exceed a threshold, thereby improving data retrieval accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a default read voltage is used for all temperature conditions, then the device complexity is reduced, but the reliability of data reading deteriorates due to temperature-induced threshold voltage shifts
Solution Approach 1:
The patent implements dynamic read voltage adjustment by storing multiple read voltages in a voltage table and selecting the appropriate voltage based on temperature information. The controller dynamically changes the read voltage from a default value to a temperature-compensated value when temperature shifts are detected, thereby maintaining reliable data reading across varying temperature conditions without requiring complex hardware modifications.
Solution Approach 2:
The patent changes the electrical parameter (read voltage) based on temperature conditions. By storing different read voltages corresponding to different temperature ranges in a voltage table and selecting the appropriate voltage based on temperature information, the system compensates for temperature-induced threshold voltage shifts in memory cells, thereby maintaining reading reliability without increasing device complexity.
2Reliability
If temperature-based voltage adjustment is implemented, then the reliability of data reading is improved, but the device complexity increases due to additional temperature tables and voltage tables
Solution Approach 1:
The patent performs preliminary action by pre-storing multiple read voltages corresponding to different temperature ranges in a voltage table before actual operation. When temperature information is obtained, the controller directly selects the appropriate pre-stored voltage without requiring complex real-time calculations or adjustments, thereby improving reading reliability while minimizing the increase in device complexity.
Solution Approach 2:
The patent introduces a voltage table as an intermediary data structure that maps temperature ranges to appropriate read voltages. This intermediary table simplifies the control logic by providing a direct lookup mechanism rather than requiring complex control algorithms, thereby improving reliability through temperature compensation while keeping the device complexity manageable.
3Productivity
If a first read operation is performed with default voltage and fail bits are detected, then the productivity is maintained through quick initial read, but the reliability deteriorates when fail bits exceed threshold due to temperature effects
Solution Approach 1:
The patent implements periodic action through a two-stage reading process. First, a quick initial read operation is performed with the default read voltage to maintain productivity. If fail bits are detected and exceed the threshold, a second read operation is periodically performed with a temperature-compensated read voltage selected from the voltage table, thereby ensuring data integrity when temperature effects become significant.
Solution Approach 2:
The patent uses feedback by monitoring the number of fail bits from the first read operation. When fail bits exceed a predetermined threshold, the system triggers a second read operation with temperature-compensated voltage. This feedback mechanism ensures that productivity is maintained through quick initial reads while reliability is preserved by activating voltage adjustment only when temperature-induced errors are detected.
Data Source
AI summary
A memory system may include a memory device including a plurality of memory cells, and a controller suitable for controlling the memory device to perform a first read operation by applying a first read voltage to a target memory cell in which data corresponding to a read command provided from a host is stored. When the number of fail bits in first read data read through the first read operation is greater than or equal to a preset threshold value, the controller may check outside temperature recorded in a temperature table based on real time clock (RTC) information and country information which are provided from the host, set a second read voltage based on the outside temperature and a read voltage table, and control the memory device to perform a second read operation by applying the second read voltage to the target memory cell.