Memory System Adjacent Word Line Refresh for Data Integrity
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Solution Overview
Problem
Data stored in memory cells adjacent to frequently activated word lines is prone to loss due to leakage current and electromagnetic interference, leading to data damage when word lines toggle between active and precharge states.
Innovation Solution
A memory system with a control unit that selectively activates and refreshes adjacent word lines, including redundancy word lines, during a target refresh operation to prevent data loss by managing the activation and precharge states of word lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a word line is frequently activated to improve data access speed, then productivity is improved, but adjacent memory cells suffer from leakage current and electromagnetic interference causing data loss
Solution Approach 1:
The patent applies preliminary action by performing refresh operations on adjacent word lines before data loss occurs. The memory controller detects frequently activated word lines and proactively refreshes adjacent memory cells during idle periods or low-activity times, preventing data loss before it happens due to leakage current and electromagnetic interference.
Solution Approach 2:
The patent applies local quality by selectively refreshing only those adjacent memory cells that are affected by frequently activated word lines, rather than performing blanket refresh operations on the entire memory array. This targeted approach addresses the specific local problem areas while maintaining overall system efficiency.
2Reliability
If redundancy word lines are used to replace normal word lines for improving reliability, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies copying by creating redundancy word lines that are copies of normal word lines. These redundant copies are used specifically for refresh operations on adjacent cells, providing a simple replication strategy that improves reliability without requiring complex error correction codes or sophisticated redundancy management schemes.
3Reliability
If adjacent word lines are continuously refreshed to prevent data loss, then reliability is improved, but energy consumption increases
Solution Approach 1:
The patent applies partial action by refreshing only the necessary subset of adjacent word lines that are affected by frequently activated word lines, rather than continuously refreshing the entire memory array. The refresh frequency and scope are adjusted to match the actual need, avoiding excessive refresh operations on cells that do not require them.
Solution Approach 2:
The patent applies periodic action by performing refresh operations at strategically chosen intervals based on the activation pattern of word lines. Instead of continuous refreshing, the system monitors word line activation and triggers refresh operations periodically when adjacent cells are at risk, balancing reliability with energy efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents data loss and damage in memory cells adjacent to frequently activated word lines by ensuring proper refresh operations, even when redundancy word lines replace normal word lines, thereby maintaining data integrity.
Implementation Method 1
Since leakage current occurs due to a PN junction of a metal oxide semiconductor (MOS) transistor, the amount of charges initially stored in the capacitor is lost
Implementation Method 2
data stored in memory cells coupled with adjacent word lines may be damaged because electromagnetic waves generated when a word line toggles between an active state and a precharge state induce and drain electrons stored in the cell capacitors
Data Source
AI summary
A memory includes a first cell block comprising a plurality of first word lines and one or more first redundancy word lines for replacing at least one of the plurality of first word lines; a second cell block comprising a plurality of second word lines and one or more second redundancy word lines for replacing at least one of the plurality of second word lines; and a control unit suitable for sequentially receiving one or more input addresses, during a target refresh section, selecting one of the first cell block and the second cell block and a word line included in the selected cell block in response to a first input address, and activating one or more adjacent word lines adjacent to the selected word line, which is selected based on the first input address, when the selected word line is adjacent to the redundancy word line, wherein the adjacent word lines comprise the redundancy word line.