Pre-lockout Read for Reverse Order Read in Memory
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Solution Overview
Problem
Non-volatile memory apparatuses face challenges in compatibility with lockout mode during Reverse Order Read (ROR) operations, which affects read efficiency and power consumption.
Innovation Solution
Implementing a pre-lockout read mechanism with specific sensing levels to determine active memory cells, allowing for lockout mode operation during ROR, reducing the number of conductive cells and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If Reverse Order Read (ROR) operation is performed without pre-lockout read, then read operation can be completed, but power consumption increases and read efficiency decreases due to inability to lockout conductive cells
Solution Approach 1:
A pre-lockout read operation is performed before the main ROR operation to identify and lockout conductive cells in advance. This preliminary action determines which cells will be conductive during the ROR operation, allowing the system to prepare lockout signals that prevent these cells from contributing to the read operation, thereby reducing power consumption while maintaining operational simplicity
2Measurement precision
If pre-lockout read is implemented with multiple sensing levels, then cell locking accuracy improves and power consumption reduces, but sensing operation complexity increases
Solution Approach 1:
The sensing operation is segmented into multiple distinct sensing levels (first sensing level, second sensing level, third sensing level) with different voltage thresholds. Each sensing level targets specific data states (first data state, second data state) and identifies different sets of conductive cells. This segmentation allows precise identification of cells to be lockedout without requiring complex single-stage sensing
3Productivity
If lockout mode is enabled during ROR operation, then read efficiency improves and power consumption reduces, but compatibility issues arise without proper pre-lockout mechanism
Solution Approach 1:
The pre-lockout read operation performs preliminary identification of conductive cells before the main ROR operation begins. By determining which cells will be conductive at different sensing levels in advance, the system can establish lockout signals that enable ROR operation to proceed efficiently with reduced power consumption, resolving the compatibility issue between ROR and lockout mode
Solution Approach 2:
The system changes sensing parameters (voltage levels, threshold values) across different sensing operations to identify cells at different data states. The first sensing level uses one set of parameters for the first data state, while the second sensing level uses different parameters for the second data state, allowing flexible adaptation to various read conditions and enabling lockout mode compatibility
Data Source
AI summary
A method for a pre-lockout read for a reverse order read operation with lockout mode is disclosed. The method comprises: performing a pre-lockout read at a first sensing level to determine which memory cells of the set of memory cells are on in response to the first sensing level being applied to a selected word line; performing a first sensing operation on the selected word line at a second sensing level including sensing memory cells of the set of memory cells determined to be off in response to the pre-lockout read; and performing a second sensing operation on the selected word line at a third sensing level including sensing memory cells of the set of memory cells determined to be on in response to the pre-lockout read, where the first sensing level is of a value between the second sensing level and the third sensing level.