Memory Target Refresh Reduces Word Line Disturbance
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Solution Overview
Problem
Memory cells experience data loss due to word line disturbance caused by frequent activation and precharging of word lines, leading to charge fluctuations in adjacent capacitors, which can result in data corruption before a target refresh operation is performed.
Innovation Solution
A memory system that includes a control unit for sequentially refreshing word lines and identifying highly active word lines, enabling a first and second refresh signal to refresh both the counting and target addresses at random times, thereby reducing word line disturbance by performing a target refresh operation at a random time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If word lines are frequently activated and precharged to enable high-speed memory operations, then memory operation speed is improved, but charge fluctuations in adjacent capacitors occur causing data corruption
Solution Approach 1:
The patent performs a target refresh operation on adjacent memory cells before data corruption occurs. The control unit identifies highly active word lines and proactively refreshes adjacent cells that are vulnerable to word line disturbance, preventing data loss before it happens during frequent word line activations
Solution Approach 2:
The patent applies preliminary anti-action by performing refresh operations on adjacent memory cells in advance to counteract the harmful effects of upcoming word line activations. The control unit predicts which cells will be affected by highly active word lines and refreshes them beforehand to neutralize the potential data corruption
2Reliability
If sequential refresh operation is performed on all word lines, then data integrity is maintained, but memory refresh time increases
Solution Approach 1:
The patent applies local quality by performing refresh operations selectively only on memory cells adjacent to highly active word lines, rather than uniformly refreshing all memory cells. The control unit identifies specific vulnerable cells and applies refresh operations only to those locations, reducing overall refresh time while maintaining data integrity where it is most needed
Solution Approach 2:
The patent uses partial action by performing refresh operations on a subset of memory cells (those adjacent to highly active word lines) rather than all cells. This partial refresh approach is sufficient to prevent data corruption in vulnerable cells while significantly reducing the time required compared to full sequential refresh
Data Source
AI summary
A memory may include a plurality of word lines coupled to one or more memory cells; a target address generation unit suitable for generating one or more target addresses using a stored address; and a control unit suitable for sequentially refreshing the plurality of word lines in response to a refresh command which is periodically inputted, and refreshing a word line corresponding to the target address in response to the refresh command at a random time.