Flash Memory Temperature Compensation for Bit Error Reduction
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Solution Overview
Problem
Non-volatile data storage devices, such as flash SSDs, face increased bit error rates due to temperature variations between programming and reading, causing shifting and widening of cell voltage distributions, which existing technologies have not adequately addressed.
Innovation Solution
The implementation of temperature compensation techniques, including measuring and storing write temperatures, adjusting read thresholds, and applying compensation schemes such as urgent refresh, using slower trims, and error correction coding, to mitigate the effects of temperature differences during data retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple bits are stored in each flash memory cell to increase storage density, then storage density is improved, but bit error rate increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting read threshold voltages based on temperature conditions. The system monitors temperature and modifies read parameters (threshold voltages) to compensate for temperature-induced shifts in cell voltage distributions, thereby maintaining low bit error rates while storing multiple bits per cell for high storage density
2Adaptability or versatility
If data is read at a different temperature than programming temperature, then operational flexibility is improved, but cell voltage distributions shift and widen causing increased bit error rate
Solution Approach 1:
The patent implements preliminary action by measuring and storing the programming temperature along with the data. This stored temperature information is later used to calculate appropriate read threshold voltage adjustments, allowing the system to prepare compensation parameters in advance and apply them during read operations at different temperatures
Solution Approach 2:
The system employs feedback by continuously monitoring temperature conditions and using this information to dynamically adjust read parameters. The temperature measurement feeds back into the control logic, which then modifies threshold voltages to compensate for temperature-induced voltage distribution changes, maintaining reliable reads across varying temperature conditions
Data Source
AI summary
A data storage device is configured to mark data for refresh in response to determining that a first measured temperature associated with writing the data to the memory exceeds a first threshold. The data storage device is further configured to refresh the marked data in response to determining that a second measured temperature associated with the memory is below a second threshold.