DRAM Self-Refresh Skip Control for Short Idle Intervals
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Solution Overview
Problem
Existing semiconductor memory devices, such as DRAM, face issues with unnecessary self-refresh operations due to frequent and short-duration self-refresh entry and exit commands, leading to logic errors and increased power consumption.
Innovation Solution
A semiconductor memory device with a self-refresh skip circuit that autonomously determines the duration between self-refresh entry and exit commands, skipping operations when the duration is shorter than a reference time, thereby reducing unnecessary self-refresh operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DRAM device performs self-refresh operation frequently based on self-refresh entry commands, then data retention is maintained, but unnecessary operations occur leading to logic errors and increased power consumption
Solution Approach 1:
The patent introduces a timer that starts counting from the moment a self-refresh entry command is received. This preliminary timing action allows the system to evaluate whether the self-refresh operation should be executed or skipped based on the duration between entry and exit commands, preventing unnecessary operations while ensuring data retention when needed.
Solution Approach 2:
The patent changes the parameter of command duration by introducing a reference time threshold. When the duration between self-refresh entry and exit commands is shorter than this reference time, the system determines that the operation is unnecessary and skips it. This parameter-based decision-making reduces power consumption while maintaining data retention reliability.
2Reliability
If self-refresh operations are performed repeatedly without considering duration, then data retention is maintained, but logic errors occur due to unnecessary operations
Solution Approach 1:
The timer starts counting immediately when a self-refresh entry command is received, creating a preliminary evaluation period. This allows the system to check whether the corresponding exit command arrives within the reference time, and only then execute the self-refresh operation, thereby preventing logic errors from unnecessary repeated operations.
Solution Approach 2:
By introducing the reference time parameter and comparing the actual duration against it, the system makes intelligent decisions about whether to execute self-refresh operations. This parameter-based approach filters out unnecessary operations that would cause logic errors while preserving data retention functionality.
3Loss of energy
If the system adds duration checking logic to skip unnecessary self-refresh operations, then power consumption and logic errors are reduced, but device complexity increases
Solution Approach 1:
The patent merges the timer functionality with the existing refresh control circuitry. The timer is integrated into the control circuit that manages self-refresh operations, combining timing functions with control logic. This merging approach reduces overall device complexity compared to having separate independent timing circuits, while still achieving power savings through duration-based decision making.
Data Source
AI summary
A self-refresh method of a semiconductor memory device includes: receiving a self-refresh entry command associated with a self-refresh operation; counting an elapsed time from a time of receiving the self-refresh entry command; and skipping the self-refresh operation depending on whether a self-refresh exit command is received before the counted elapsed time exceeds a reference time.