MRAM Read Circuit Position-Based Determination Levels
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Solution Overview
Problem
Magnetic interference between memory cells in Magnetoresistive Random Access Memory (MRAM) affects the reliability of data reading, leading to errors due to shifts in resistance values of magnetoresistive effect elements, especially in high-density storage configurations where cell proximity increases magnetic field interactions.
Innovation Solution
The magnetic memory system dynamically adjusts the determination level for reading data based on the position of the memory cell within the cell array, utilizing multiple reference potentials and currents to account for varying magnetic interference, thereby selecting an appropriate read level corresponding to the cell's location and minimizing interference effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If memory cells are densely packed to increase storage density, then storage capacity is improved, but magnetic interference between cells increases causing reading errors
Solution Approach 1:
The patent applies local quality by setting different determination levels for different regions within the cell array. Specifically, memory cells are divided into first through fourth regions based on their positions, and each region is assigned a specific determination level (first, second, third, or fourth level) that accounts for the local magnetic interference characteristics. This allows the reading operation to be optimized for each local region, maintaining high storage density while compensating for position-dependent magnetic interference effects.
2Device complexity
If a single determination level is used for all memory cells, then device complexity is reduced, but reading accuracy decreases due to varying magnetic interference across the array
Solution Approach 1:
The patent segments the cell array into multiple regions (first, second, third, and fourth regions) based on positional characteristics, and assigns different determination levels to each region. This segmentation approach allows the system to achieve high reading accuracy by accounting for local magnetic interference variations without requiring excessively complex control circuits. The segmentation is implemented through a read control circuit that selects appropriate determination levels based on the position of the target memory cell.
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
This approach enhances the reliability of data reading by accurately determining the resistance state of magnetoresistive effect elements, even in densely packed arrays, by considering the specific magnetic interference patterns across different regions of the cell array, thus preventing errors caused by magnetic interference.
Implementation Method 1
An MRAM contains a magnetoresistive effect element in a memory cell. A magnetoresistive effect element includes two magnetic layers (ferromagnetic layers) and a nonmagnetic layer provided therebetween. Data of '1' or '0' is stored in a memory cell depending on a magnetized state of the two magnetic layers of the magnetoresistive effect element
Data Source
AI summary
According to one embodiment, a magnetic memory includes a cell array includes a plurality of memory cells, each memory cell including a magnetoresistive effect element; and a read circuit to read data from a memory cell selected based on an address signal from among the memory cells. The read circuit selects one determination level from among a plurality of determination levels corresponding to a position of a magnetoresistive effect element in the cell array and uses the selected determination level to perform reading of the data.