DRAM Refresh Control via Cell Retention Data Storage
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Solution Overview
Problem
Current memory systems face high current consumption during refresh operations due to uniform refresh methods applied to all memory cells, regardless of their data retention times, leading to unnecessary power usage, especially in mobile devices where low power consumption is critical.
Innovation Solution
A memory system that stores cell characteristic information in a non-volatile memory within a Dual In-line Memory Module, allowing for controlled refresh operations based on the stored data, thereby optimizing refresh cycles for each memory cell to reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If uniform refresh operation is performed on all memory cells, then all memory cells are refreshed, but unnecessary current consumption occurs
Solution Approach 1:
The patent applies local quality by dividing memory cells into different groups based on their retention characteristics (first group with longer retention time, second group with shorter retention time). Each group receives customized refresh operations tailored to its specific needs, rather than applying uniform refresh to all cells. This allows the system to refresh only the necessary cells with appropriate frequency, eliminating unnecessary current consumption from over-refreshing cells with long retention times.
Solution Approach 2:
The patent segments the memory cell population into multiple groups with different retention characteristics. By segmenting cells based on their individual retention times, the system can apply differentiated refresh strategies to each segment. This segmentation enables the controller to perform refresh operations selectively on specific groups rather than uniformly on all cells, thereby reducing overall power consumption while maintaining data integrity.
2Reliability
If refresh operation is performed frequently, then data retention is maintained, but current consumption increases
Solution Approach 1:
The patent changes the refresh operation parameters (frequency and timing) based on the retention characteristics of different memory cell groups. The controller adjusts refresh intervals dynamically - applying longer intervals to cells with long retention times and shorter intervals to cells with short retention times. This parameter adaptation allows the system to maintain reliable data retention while minimizing energy loss by avoiding excessive refresh operations.
Solution Approach 2:
The patent applies partial action by performing refresh operations only on necessary memory cell groups rather than all cells. Cells with long retention times may skip refresh operations or receive less frequent refreshes, while only cells with short retention times receive full refresh attention. This partial approach eliminates wasteful energy expenditure on cells that don't require frequent refreshing.
3Ease of operation
If same refresh operation is applied to all memory cells, then refresh simplicity is maintained, but power efficiency decreases
Solution Approach 1:
The patent introduces dynamics into the refresh operation by making refresh timing and frequency adaptive rather than static. The controller dynamically adjusts refresh schedules based on detected retention characteristics of different cell groups. This dynamic approach maintains operational simplicity from the user perspective while internally optimizing power efficiency through automated, characteristic-based refresh scheduling.
Solution Approach 2:
The patent implements feedback mechanisms where the system detects and stores retention characteristics of memory cells, then uses this information to control refresh operations. The controller receives feedback about cell performance and adjusts refresh strategies accordingly. This feedback loop enables the system to maintain simple operation interfaces while achieving improved power efficiency through intelligent, data-driven refresh management.
Data Source
AI summary
A memory system is disclosed, which relates to a technology for reducing current consumption needed to perform a refresh operation in a Dual In-line Memory Module. The memory system includes a memory module, which includes a volatile memory and a non-volatile memory, and a host configured to provide a refresh command to the memory module during the refresh operation. The memory module is configured to store cell characteristic information of the volatile memory in the non-volatile memory in an idle state, and control a refresh operation of the volatile memory in response to the cell characteristic information.