DRAM Refresh Control Unit for Row Hammer Mitigation
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Solution Overview
Problem
The frequent occurrence of 'row hammer' in DRAM memory devices leads to data damage due to excessive discharge of electric charges, and shortening the refresh interval to prevent this increases power consumption.
Innovation Solution
A semiconductor memory device with a control unit that dynamically adjusts the refresh operation interval based on the frequency of read/write access requirements, shortening the interval during high access frequencies to protect data without increasing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the refresh interval is shortened to prevent row hammer, then data reliability is improved, but power consumption increases
Solution Approach 1:
The refresh interval is made dynamic rather than fixed. The control unit adjusts the refresh interval based on the access frequency to specific row addresses. When access frequency is high, the refresh interval is shortened to prevent row hammer; when access frequency is low, the refresh interval is extended to reduce power consumption. This dynamic adjustment resolves the contradiction between data reliability and power consumption.
Solution Approach 2:
The refresh interval parameter is changed based on operating conditions. The control unit monitors access frequency and modifies the refresh interval parameter accordingly. By changing this parameter dynamically, the system achieves both data protection (when needed) and power savings (when not needed), resolving the technical contradiction.
2Reliability
If the refresh operation is performed frequently, then row hammer is prevented, but power consumption increases
Solution Approach 1:
Instead of uniformly refreshing all memory rows at high frequency, the control unit applies refresh operations selectively based on local access patterns. Only rows with high access frequency undergo frequent refresh, while other rows use the standard refresh interval. This localized approach prevents row hammer where needed while minimizing power consumption elsewhere.
Solution Approach 2:
The system performs partial refresh actions rather than complete refresh cycles for all memory. The control unit determines which specific rows need refresh based on access frequency monitoring, and performs refresh operations only on those rows. This partial action approach provides sufficient protection against row hammer while avoiding unnecessary power consumption from redundant refresh operations.
Data Source
AI summary
A semiconductor memory device is provided. The semiconductor memory device can suppress increases in power consumption. As a result, damage to the data normally caused by row problems can be prevented. The semiconductor memory device includes a control unit. The control unit controls the time interval for refreshing the memory. If the frequency of a read/write access requirement to the memory during a predetermined period is higher, then the control unit shortens the interval between memory refresh operations.