Volatile Memory Cell Life Extension via Dynamic Wordline Voltage
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Solution Overview
Problem
Volatile memory devices, such as DRAM, experience reduced life expectancy due to memory cell deterioration, leading to performance degradation and shortened operational life.
Innovation Solution
A method is implemented where a control logic in the volatile memory device performs a life test to determine the state of memory cells, and if found to be in a deteriorated state, the wordline voltage is reduced or the supply voltage is lowered to extend the life expectancy of the memory cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If normal wordline voltage is applied to memory cells, then read/write operations function properly, but memory cell deterioration accelerates and life expectancy reduces
Solution Approach 1:
The patent implements dynamic voltage adjustment by switching between normal voltage mode and life extension mode based on the operational state and age of the memory device. The control logic dynamically modifies the wordline voltage level according to whether the device is undergoing life testing or normal operation, and whether the memory cells are in a normal or shrink-life state, thereby optimizing both performance and reliability at different operational stages
Solution Approach 2:
The patent changes the voltage parameter of the wordline signal to extend memory cell life. When memory cells are determined to be in a shrink-life state, the wordline voltage is reduced from the normal level to a lower level during life extension mode, thereby reducing stress on the memory cells and slowing down deterioration while maintaining basic functionality
2Reliability
If life test is performed on memory cells, then life expectancy can be predicted, but operational time is consumed
Solution Approach 1:
The patent performs life tests and determines the life state of memory cells in advance before normal operation begins. The control logic executes life testing operations to predict whether memory cells will enter a shrink-life state, allowing the system to proactively switch to life extension mode and prevent performance degradation before it occurs
Solution Approach 2:
The patent implements a feedback mechanism where the results of life tests are used to control subsequent voltage adjustment decisions. The control logic continuously monitors the life state of memory cells based on test results and automatically adjusts the wordline voltage accordingly, creating a closed-loop system that optimizes both reliability and operational efficiency
Data Source
AI summary
A method for extending life expectancy of a volatile memory device includes performing a life test corresponding to memory cells included in the volatile memory device, determining whether the memory cells have a normal life state or a shrink-life state indicating a life expectancy that is reduced relative to the normal life state based on a result of the life test, and decreasing a wordline voltage, which is applied to a wordline connected to the memory cells, to a first voltage that is less than a second voltage that is applied to the wordline in the normal life state during a read operation or a write operation responsive to determining that the memory cells have the shrink-life state.