Ferroelectric Memory Refresh During Power-Down State
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Solution Overview
Problem
Ferroelectric memories experience data loss due to accumulated disturbances when power is cycled before reaching the prescribed access frequency for refresh operations, leading to data disappearance.
Innovation Solution
A memory system with a refresh portion that can read and rewrite data in a power-down state, including a power-down detecting portion to trigger refresh operations, a row decoder for controlling word lines, and frequency detecting portions to manage access frequencies, ensuring data integrity across power cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the memory performs refresh operations only when access frequency reaches a prescribed number of times, then the refresh operation is performed efficiently, but data may disappear when power is cycled before reaching the prescribed access frequency
Solution Approach 1:
The refresh operation is performed in advance during the power-down state, before the power is turned off. This preliminary action ensures that data is refreshed before potential disturbance occurs during power cycling, preventing data disappearance while maintaining efficient refresh operation
Solution Approach 2:
The memory performs a refresh operation that counteracts the potential disturbance before it can occur. By refreshing data during the power-down state, the system preemptively prevents the accumulation of disturbances that would otherwise lead to data loss during power cycling
2Loss of energy
If the memory is repetitively subjected to power-down operations before access frequency reaches prescribed number of times, then power consumption is reduced, but disturbances accumulate in memory cells causing data disappearance
Solution Approach 1:
The refresh operation is executed during the power-down state, performing the necessary data preservation action before power is restored. This allows the memory to remain in a low-power state while still maintaining data integrity through preliminary refreshing
Solution Approach 2:
The memory system automatically detects the power-down state and autonomously performs the refresh operation without requiring external intervention. This self-service mechanism ensures data protection during power cycling while maintaining energy efficiency
Data Source
AI summary
A memory capable of preventing a memory cell from disappearance of data resulting from accumulated disturbances is obtained. This memory comprises a nonvolatile memory cell and a refresh portion for rewriting data in the memory cell. The refresh portion reads data from and rewrites data in the memory cell in a power-down state.