Semiconductor Memory Device Refresh Period Segmentation
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Solution Overview
Problem
Semiconductor memory devices, particularly DRAMs, face challenges in reducing power consumption due to the need for frequent refresh operations to maintain data retention, which increases power usage, especially in portable devices.
Innovation Solution
A semiconductor memory device that manages memory cells with varying data retention characteristics by storing refresh period information for each cell region, allowing for separate refresh periods based on retention characteristics, thereby reducing the overall refreshing frequency and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a refresh period becomes shorter, then data retention characteristic is improved, but power consumption is increased
Solution Approach 1:
The patent segments the cell array into multiple cell regions (first cell region, second cell region, etc.) and assigns different refresh periods to each region based on their individual retention characteristics. This segmentation allows weak retention regions to be refreshed more frequently while strong retention regions use longer refresh periods, resolving the contradiction between data retention and power consumption.
Solution Approach 2:
The patent applies local quality by tailoring the refresh period to each specific cell region according to its retention characteristics. Instead of using a uniform refresh period for the entire array, each region receives customized refresh timing based on its local properties, optimizing the balance between retention and energy usage for each region.
2Device complexity
If a uniform refresh period is used for all cell regions, then device complexity is reduced, but power consumption cannot be optimized
Solution Approach 1:
The patent introduces dynamic refresh period management where the refresh timing is not fixed uniformly but is adjusted based on the retention characteristics of different cell regions. The refresh controller dynamically selects appropriate refresh periods for different regions, enabling power optimization while managing complexity through structured dynamics.
Solution Approach 2:
The patent employs feedback mechanisms where retention characteristic information is stored and used to determine refresh periods. The system uses feedback from retention testing and characterization data to automatically configure optimal refresh schedules for each cell region, reducing manual complexity while achieving power optimization.
Data Source
AI summary
A semiconductor memory device which stores refresh period information thereby adjusting a refresh period and a method of operating the same. The semiconductor memory device includes a cell array and a refresh information storing unit. The cell array includes one or more cell regions each having a plurality of memory cells. The refresh information storing unit is configured to store first information including a first refresh period and second information including a second refresh period in correspondence to each of the cell regions. Memory cells included in each of the cell regions are refreshed at the first refresh period according to the first information in a first refresh time band and are refreshed at the second refresh period according to the second information in a second refresh time band.