Resistive Memory Sensing via Multiple Pass Voltage Segmentation
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Solution Overview
Problem
Existing resistive memory sensing methods face challenges in accurately determining the data state of resistive memory cells due to significant voltage drops across the selected word line, which can reduce sensing accuracy and the number of distinguishable resistance states.
Innovation Solution
A voltage based multiple pass sensing method is employed, where different sense voltages are applied to a group of resistive memory cells, and for each successive pass, data lines corresponding to cells that conducted a threshold amount of current in the previous pass are disabled, reducing the current on the word line and improving sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single pass sensing operation is used to determine data states of resistive memory cells, then the sensing operation is simple and fast, but voltage drops across the word line reduce sensing accuracy and the number of distinguishable resistance states
Solution Approach 1:
The sensing operation is divided into multiple passes, each detecting a specific range of resistance states. The first pass detects high-resistance states, the second pass detects intermediate states, and the third pass detects low-resistance states. This segmentation allows accurate detection of all resistance states while maintaining acceptable word line voltage drops in each individual pass.
Solution Approach 2:
The sensing operation is performed periodically in discrete passes rather than continuously in a single operation. Each pass applies a sense voltage and detects current for a specific duration, then pauses before the next pass. This periodic approach allows the system to manage word line voltage drops by resetting between passes while accumulating detection information.
2Measurement precision
If multiple different sense voltages are applied in successive passes to improve sensing accuracy, then more resistance states can be distinguished, but the sensing operation time increases
Solution Approach 1:
Each sensing pass applies a sense voltage that is sufficient to detect a specific subset of resistance states but not necessarily all states. The first pass uses a first sense voltage optimized for detecting high-resistance states, the second pass uses a second sense voltage for intermediate states, and the third pass uses a third sense voltage for low-resistance states. This partial action approach allows the system to detect all states across multiple passes without requiring each pass to be excessively long or complex.
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 reduces voltage drop on the word line, enhances sensing accuracy, and increases the number of distinguishable resistance states within a sensing window, while also reducing current draw on data lines.
Implementation Method 1
providing an indication of those cells of the group that conduct at least a threshold amount of current responsive to one of a number of different sense voltages applied to the selected conductive line
Data Source
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AI summary
The present disclosure includes resistive memory sensing methods and devices. One such method includes performing a voltage based multiple pass sensing operation on a group of cells coupled to a selected conductive line of an array of resistive memory cells. The voltage based multiple pass sensing operation can include providing an indication of those cells of the group that conduct at least a threshold amount of current responsive to one of a number of different sense voltages successively applied to the selected conductive line during each of a corresponding number of the multiple passes, and for each successive pass of the multiple passes, disabling data lines corresponding to those cells determined to have conducted the threshold amount of current in association with a previous one of the multiple passes.