Memory Row Self-Refresh Control for Faster Command Exit
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Solution Overview
Problem
Existing memory devices face inefficiencies in power consumption and performance due to the need to wait for self-refresh operations to complete before processing commands, leading to prolonged exit times from self-refresh to valid commands.
Innovation Solution
The memory device is designed to perform self-refresh operations in units of individual word lines, allowing it to stop refresh operations mid-cycle and process commands immediately, thereby reducing power consumption and shortening the time required to transition from self-refresh to valid commands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the memory device performs self-refresh operations on all rows before processing commands, then data retention is ensured, but the time to exit self-refresh and process commands is prolonged
Solution Approach 1:
The patent divides the self-refresh operation into row-specific segments. Instead of refreshing all rows uniformly before command processing, the system identifies and refreshes only the specific row that needs to be accessed, allowing other rows to remain in self-refresh state. This segmentation enables selective exit from self-refresh, reducing the overall exit time while maintaining data retention for the accessed row.
Solution Approach 2:
The patent implements dynamic control of self-refresh operations by monitoring access patterns and adjusting refresh behavior in real-time. When a row access is predicted or identified, the system dynamically transitions that specific row from self-refresh to active state, while maintaining self-refresh for other rows. This dynamic approach optimizes the balance between data retention and command processing speed.
2Loss of energy
If the memory device enters self-refresh mode during idle times, then power consumption is reduced, but the device must wait for refresh completion before resuming operations
Solution Approach 1:
The patent employs preliminary action by predicting future row access patterns and proactively managing self-refresh operations accordingly. Before the device fully enters self-refresh mode, the system identifies likely accessed rows and prepares them for quick activation. This preliminary preparation allows the device to resume operations on predicted rows faster, reducing the effective response time while maintaining power-saving self-refresh for other rows.
Solution Approach 2:
The system dynamically adjusts between power-saving self-refresh mode and active operation mode based on real-time access patterns and command predictions. When idle time is detected, the device enters self-refresh, but simultaneously monitors for upcoming accesses and dynamically transitions specific rows to active state before commands arrive, thereby reducing actual response time while maintaining overall power efficiency.
3Reliability
If the memory device refreshes multiple rows sequentially during self-refresh, then comprehensive data retention is achieved, but the time required to complete refresh operations increases
Solution Approach 1:
The patent extracts the necessary refresh operations from the complete self-refresh sequence. Instead of systematically refreshing all rows, the system identifies and extracts only the specific row refresh operations that are needed based on access patterns. This extraction approach maintains data retention for accessed rows while eliminating unnecessary refresh operations on other rows, thereby reducing the overall refresh duration.
Solution Approach 2:
The patent applies partial action by performing refresh operations on only a subset of rows rather than all rows. The system determines the minimum necessary refresh scope based on predicted or actual access patterns, refreshing only those rows that will be accessed. This partial refresh approach achieves sufficient data retention for operational needs while significantly reducing the time and energy required compared to comprehensive refresh of all rows.
Data Source
AI summary
A memory device is provided. The memory device includes: a first memory cell array including a first row and a second row; and a self-refresh circuit configured to control refresh in response to a first self-refresh entry signal, and stop refresh of the second row after refreshing the first row in response to a self-refresh exit signal.