Non-volatile Memory Dummy Cell Voltage Control
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Solution Overview
Problem
Non-volatile memory devices face inefficiencies in energy dissipation and switching speed due to the lack of effective control over dummy cells and ground select transistors during pre-charge periods, leading to suboptimal performance and energy consumption.
Innovation Solution
Incorporating dummy cells and a controller to manage gate voltages of these cells, ensuring they are below threshold voltage during pre-charge periods, which isolates cell strings and reduces energy dissipation, and using select transistor control logic to manage ground select transistors, allowing for faster switching and reduced current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If dummy cells and ground select transistors are not controlled during pre-charge periods, then device complexity is reduced, but energy dissipation increases and switching speed decreases
Solution Approach 1:
The controller proactively sets the gate voltage of dummy cells to below threshold voltage during pre-charge periods before actual memory operations begin. This preliminary action isolates cell strings in advance, preventing energy dissipation during the pre-charge phase and preparing the device for faster switching when operations start.
2Productivity
If dummy cells are controlled during pre-charge periods, then energy dissipation is reduced, but device complexity increases
Solution Approach 1:
The controller performs preliminary configuration of dummy cell gate voltages during pre-charge periods, ensuring cells are in the correct state before operations begin. This advance preparation enables faster switching speeds during actual operations without requiring complex real-time control mechanisms.
Solution Approach 2:
The control mechanism applies periodic gating signals to dummy cells at specific phases (pre-charge periods) of the memory operation cycle. This periodic control approach maintains energy efficiency only when needed, rather than continuously, thereby reducing overall device complexity while still improving switching speed during critical operation phases.
3Loss of energy
If gate voltage of dummy cells is controlled below threshold voltage during pre-charge, then energy consumption is reduced, but control precision requirements increase
Solution Approach 1:
The controller changes the voltage parameter of dummy cell gates to below threshold voltage during pre-charge periods. This parameter change effectively blocks current flow through dummy cells and isolates cell strings, reducing current consumption without requiring extremely high precision voltage control, as any voltage below the threshold suffices to achieve the isolation effect.
Data Source
AI summary
A non-volatile memory device includes a cell string, a ground select transistor, and at least one dummy cell. The cell string includes at least one memory cell. The at least one dummy cell is provided between the at least one memory cell and the ground select transistor and is connected to a bit line. A controller executes dummy cell control logic configured to control a gate voltage of the at least one dummy cell to be lower than a threshold voltage of the at least one dummy cell in at least a part of a pre-charge period.