Per-Die Temperature Compensation for Memory Read Accuracy
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Solution Overview
Problem
Conventional memory systems face increased raw bit error rates due to temperature variations between data writing and reading, which can exceed the error correction capability, especially when memory cells are programmed at one temperature range and read at another.
Innovation Solution
An adaptive temperature compensation scheme is implemented at a per-die level, calculating a temperature compensation value from voltage levels to adjust read values accurately, rather than using a general compensation value for the entire memory system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a general compensation value is used for the entire memory system, then the device complexity is reduced, but the measurement precision and error correction capability deteriorate due to temperature variations
Solution Approach 1:
The memory system is segmented into individual die-level units, each with its own temperature compensation value. Instead of applying a single general compensation value to the entire memory system, the patent calculates and stores separate compensation values for each die (e.g., tempco[0], tempco[1], tempco[2], tempco[3] for four dies). This segmentation allows each die to be compensated independently based on its specific temperature characteristics, thereby improving measurement precision while maintaining manageable device complexity through modular organization.
2Measurement precision
If temperature compensation is implemented at per-die level, then the measurement precision and error rate reduction improve, but the device complexity increases due to multiple compensation values
Solution Approach 1:
Temperature compensation values are calculated and stored in advance during manufacturing or initialization, before the memory device operates under varying temperature conditions. The patent pre-calculates compensation values based on voltage levels measured at different temperatures and stores them in lookup tables or registers. This preliminary action eliminates the need for real-time complex calculations during operation, thereby improving measurement precision without significantly increasing operational device complexity.
Solution Approach 2:
The patent changes the compensation parameter from a single general value to multiple die-specific values, and further refines it by using voltage level-based compensation values stored in lookup tables. This parameter change allows the system to select the appropriate compensation value based on the actual voltage level being read, improving measurement precision while managing device complexity through efficient parameter organization and selection mechanisms.
3Reliability
If error correction codes are used to handle temperature-induced errors, then the reliability improves, but the productivity decreases due to additional processing overhead
Solution Approach 1:
Temperature compensation is applied as a preliminary anti-action to prevent temperature-induced voltage shifts from causing errors in the first place. By adjusting the read voltage based on pre-calculated compensation values before the actual data reading occurs, the patent proactively counteracts the harmful effects of temperature variations. This preventive approach reduces the need for subsequent error correction processing, thereby improving reliability while maintaining productivity by avoiding the overhead of extensive error correction operations.
Data Source
AI summary
In one embodiment, a memory system receives a request to perform a memory access operation, the request identifying a memory cell in a segment of the memory system comprising at least a portion of the memory device. The system determines that an operating temperature of the memory device satisfies a threshold criterion. Responsive to determining that the operating temperature of the memory device satisfies the threshold criterion, the system determines a temperature compensation value corresponding to an access control voltage adjustment value specific to the segment of the memory system. The system adjusts, based on an amount represented by the temperature compensation value, an access control voltage applied to the memory cell during the memory access operation.