Adaptive Refresh Control Circuit for DRAM Power Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor memory devices, such as DRAM, face data degradation due to charge leakage, necessitating periodic refresh operations to prevent read errors, but existing methods lack efficient strategies to adapt refresh times based on command availability.
Innovation Solution
A method and circuit configuration that perform a fast refresh operation when a command other than a refresh command is applied and switch to a longer normal refresh operation when no such command is present, allowing adaptive refresh timing to optimize power consumption and reduce errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a normal refresh operation with longer refresh time is performed, then memory cell stability is improved, but power consumption increases and command flexibility is reduced
Solution Approach 1:
The refresh control circuit dynamically adjusts the refresh operation mode between fast refresh and normal refresh based on real-time detection of command signals. When a command signal is detected during refresh cycles, the system switches to fast refresh mode with shorter refresh time to maintain command flexibility. When no command signals are present, it transitions to normal refresh mode with longer refresh time to enhance memory cell stability. This dynamic adaptation resolves the contradiction by making refresh timing flexible rather than fixed.
Solution Approach 2:
The invention changes the refresh time parameter adaptively based on command signal presence. The refresh control circuit monitors command signals and adjusts the refresh cycle duration: using shorter refresh times (fast refresh) when commands are present, and longer refresh times (normal refresh) when commands are absent. This parameter change strategy allows the system to optimize between stability and power consumption by selecting appropriate refresh timing parameters for different operational conditions.
2Adaptability or versatility
If a fast refresh operation with shorter refresh time is performed, then command flexibility is improved, but memory cell stability deteriorates
Solution Approach 1:
The refresh control circuit implements dynamic mode switching between fast refresh and normal refresh operations based on command signal detection. When command signals are detected during refresh cycles, the system automatically selects fast refresh mode to maintain command flexibility and responsiveness. When no command signals are present, it switches to normal refresh mode to ensure adequate memory cell stability. This dynamic behavior allows the system to adapt refresh timing to operational requirements rather than using a fixed refresh schedule.
Solution Approach 2:
The invention dynamically changes the refresh time parameter based on the presence of command signals. The refresh control circuit detects command signals and adjusts refresh cycle duration accordingly: using shorter refresh time parameters (fast refresh) when commands are present to maintain flexibility, and longer refresh time parameters (normal refresh) when commands are absent to improve stability. This conditional parameter adjustment resolves the contradiction by making refresh timing adaptive to system state.
3Reliability
If refresh operations are performed continuously without adaptation, then memory cell stability is maintained, but power consumption increases unnecessarily
Solution Approach 1:
The refresh control circuit implements dynamic adaptation of refresh operations by detecting command signals and adjusting refresh timing accordingly. Instead of performing continuous normal refresh operations regardless of system state, the circuit switches between fast refresh mode (when commands are present) and normal refresh mode (when commands are absent). This dynamic behavior allows the system to maintain memory cell stability while avoiding unnecessary long refresh cycles during periods when command flexibility is needed, thereby reducing overall power consumption.
Solution Approach 2:
The invention changes refresh time parameters adaptively based on command signal presence to optimize power consumption. The refresh control circuit uses shorter refresh time parameters (fast refresh) during periods when commands are detected, and longer refresh time parameters (normal refresh) only when commands are absent. This conditional parameter adjustment ensures that extended refresh operations are performed only when necessary for stability, rather than continuously, thereby reducing unnecessary energy loss while maintaining reliability.
4Reliability
If longer refresh time is used, then memory cell stability is improved, but refresh operation speed decreases
Solution Approach 1:
The refresh control circuit dynamically adjusts refresh operation speed by switching between two modes: fast refresh mode with shorter refresh time for higher speed when commands are present, and normal refresh mode with longer refresh time for better stability when commands are absent. This dynamic speed adjustment allows the system to optimize refresh operation timing based on real-time command signal detection rather than using a fixed refresh rate, resolving the contradiction between speed and stability.
Solution Approach 2:
The invention changes the refresh time parameter conditionally based on command signal presence. The refresh control circuit uses shorter refresh time parameters (fast refresh) to maintain higher operation speed when commands are detected, and switches to longer refresh time parameters (normal refresh) to improve stability when commands are absent. This conditional parameter change strategy allows the system to achieve both high speed and high stability at different times, rather than being constrained to a single fixed refresh rate.
Data Source
AI summary
A method of refreshing a semiconductor memory device includes performing a first refresh operation for memory cells included in a memory cell array, and determining whether a command other than a refresh command is applied to the semiconductor memory device in a refresh cycle of the first refresh operation. The method further includes continuing to perform the first refresh operation when a command other the refresh command is applied to the semiconductor memory device in one refresh cycle of the first refresh operation, and performing a second refresh operation when a command other than the refresh command is not applied to the semiconductor memory device in one refresh cycle of the first refresh operation. A refresh time of the second refresh operation is greater than a refresh time of the first refresh operation.