DRAM Refresh Control Circuit Position-Based Grouping
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Solution Overview
Problem
Conventional semiconductor memory devices face challenges in managing refresh intervals effectively due to temperature variations across different positions of DRAM chips in a memory system, leading to inefficient data retention and increased complexity with temperature sensing circuits.
Innovation Solution
A refresh control circuit classifies semiconductor memory devices into groups based on their position, assigning distinct auto and self-refresh intervals to each group, allowing for optimized refresh operations based on temperature differences, thereby improving data retention and reducing current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a temperature sensor is provided inside the DRAM chip to control refresh interval according to temperature, then the refresh operation can be adjusted according to temperature, but the circuit complexity increases and reliability decreases
Solution Approach 1:
The temperature sensing function is extracted from the DRAM chip and relocated to an external device. The DRAM chip no longer contains internal temperature sensors, instead relying on external devices to detect temperature and control refresh operations, thereby reducing internal circuit complexity while maintaining temperature-adaptive refresh capability
Solution Approach 2:
An external device acts as an intermediary between the temperature environment and the DRAM chip. This intermediary device performs temperature sensing and generates control signals to adjust refresh intervals, eliminating the need for complex internal temperature sensing circuits while achieving the same adaptive refresh objective
2Quantity of substance
If DRAM chips are positioned in a narrow area to increase memory density, then memory capacity increases, but temperature difference according to position becomes more severe
Solution Approach 1:
The refresh interval is customized according to the local temperature conditions of each DRAM chip's position. Chips in different spatial locations receive different refresh intervals based on their specific thermal environments, with chips in hotter regions receiving more frequent refresh operations to compensate for increased charge leakage
Solution Approach 2:
The memory system is segmented into multiple groups based on positional information, with each group receiving independent refresh control. This segmentation allows differentiated refresh strategies for chips in different thermal zones, addressing temperature variations across the memory module
3Reliability
If refresh interval is shortened to maintain data retention at high temperature, then data reliability improves, but current consumption increases
Solution Approach 1:
The refresh interval is made dynamic rather than fixed, automatically adjusting based on detected temperature conditions. The system transitions from static refresh timing to adaptive refresh timing, shortening intervals only when temperature increases require it, thereby maintaining data reliability while minimizing unnecessary refresh operations and current consumption
Solution Approach 2:
The refresh interval parameter is changed based on temperature conditions. The system modifies this critical parameter dynamically, using temperature information to determine appropriate refresh frequencies, thus optimizing the balance between data retention requirements and power consumption
Data Source
AI summary
A memory controller controlling a plurality of semiconductor memory devices includes a refresh control circuit controlling refresh operations of the semiconductor memory devices according to positional information of memory chips of the memory devices. The refresh control circuit classifies the semiconductor memory devices into first and second groups and sets an auto refresh interval of the semiconductor memory devices belong to the first group and an auto refresh interval of the semiconductor memory devices belong to the second group different from each other.