Semiconductor Memory Refresh Control Circuit Timing
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Solution Overview
Problem
As semiconductor memory devices, particularly DRAM, face challenges in efficiently and flexibly refreshing memory cells due to increased complexity in refresh control techniques with decreasing memory component sizes, leading to the need for improved memory performance.
Innovation Solution
The implementation of a refresh control system that includes a command control circuit and a refresh control circuit, which provide internal control signals for self-refresh and auto-refresh operations, allowing for single or double pump refresh activations within a refresh cycle, reducing circuit complexity and enabling efficient timing control for memory cell refresh.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If refresh control techniques are improved to accommodate smaller memory components, then memory performance is improved, but circuit complexity increases
Solution Approach 1:
The memory device performs refresh operations autonomously without external controller intervention. The refresh control circuit generates refresh commands and manages the refresh cycle internally, allowing the device to maintain data integrity independently. This self-service approach reduces the complexity of external control systems while maintaining high memory performance.
Solution Approach 2:
The system performs preliminary actions by precharging bit lines and preparing refresh sequences before actual refresh operations are needed. The refresh control circuit anticipates timing requirements and prepares control signals in advance, enabling efficient refresh operations without increasing circuit complexity.
2Reliability
If multiple refresh operations are implemented within a refresh cycle, then data integrity is improved, but power consumption increases
Solution Approach 1:
The system implements periodic refresh operations at optimized intervals within the refresh cycle. By performing refresh operations periodically rather than continuously, the system maintains data integrity while minimizing power consumption. The refresh control circuit timing the periodic actions to occur only when necessary.
Solution Approach 2:
The system changes operational parameters dynamically based on the refresh cycle phase. The refresh control circuit adjusts timing parameters, signal durations, and operation modes to optimize between data integrity and power consumption. This parameter optimization allows multiple refresh operations to be performed efficiently without proportionally increasing power usage.
Data Source
AI summary
A system for refresh operations in semiconductor memories, and an apparatus and method therefore, are described. The system includes, for example, memory cells in memory banks that are refreshed during a self-refresh operation or an auto refresh operation. The self-refresh operation includes a different number of refresh activations than the auto refresh operation. The system further includes a row control circuit configured to refresh the memory cells in the memory banks based on refresh control signals received from a refresh control circuit, the refresh control signals provided by the refresh control circuit based on internal control signals received by the refresh control circuit from a command control circuit. The auto refresh operation includes a per bank refresh operation configured to refresh a corresponding memory bank or an all-bank refresh operation configured to refresh all memory banks.