Memory Device Under-Drive Operation Voltage Control

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Solution Overview

Problem

Existing memory devices face challenges in reducing the time required for read and verify operations, particularly due to inefficiencies in the under-drive operation which affects the setting and distinction of memory cell states.

Innovation Solution

The memory device incorporates a row decoder capable of performing an under-drive operation by decreasing the voltage level of the selected word line and applying specific operating voltages, including ground voltage and under-drive voltage, to optimize the read and verify processes based on different memory cell states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the memory device performs traditional read operations without optimized under-drive operation, then the operation flow is simple, but the time required for read and verify operations is excessive

Engineering Contradiction:

Improvetime required for read and verify operationsVSAvoidcomplexity of row decoder and voltage control

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent segments the under-drive operation into multiple distinct voltage levels (first under-drive voltage and second under-drive voltage) and applies them at different time points during the read operation. This segmentation allows optimized timing control for different memory cell states, reducing the overall operation time without requiring complex additional hardware beyond the existing row decoder structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic voltage adjustment by changing the word line voltage from an initial level to different under-drive voltage levels at different stages of the read operation. The row decoder dynamically selects and applies appropriate voltage levels based on the operation phase, enabling adaptive optimization of read and verify times while maintaining manageable device complexity through controlled dynamic behavior.

Inventive Principle:

Principle #15Dynamics

2Measurement precision

If the memory device applies single voltage level during under-drive operation, then the control logic is simple, but the distinction between different memory cell states is insufficient

Engineering Contradiction:

Improvedistinction of memory cell statesVSAvoidvoltage generator and control logic

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies different voltage levels (first under-drive voltage and second under-drive voltage) to the word line at different time points to create locally optimized conditions for detecting different memory cell states. This local quality approach allows the system to distinguish between various states with higher precision by matching specific voltage conditions to specific detection needs, while keeping the overall control logic relatively simple through sequential voltage application.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs periodic voltage adjustments during the read operation, applying under-drive voltages at specific intervals and phases. The first under-drive voltage is applied during the initial read phase, and the second under-drive voltage is applied during the verify phase, creating a periodic pattern of voltage application that enhances state distinction capability without requiring continuously complex control mechanisms.

Inventive Principle:

Principle #19Periodic action

3Reliability

If the memory device decreases word line voltage level during under-drive operation, then the word line setting is improved, but the operation time increases

Engineering Contradiction:

Improveword line settingVSAvoidduration of under-drive operation

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

The patent applies the first under-drive voltage level before the main read operation to pre-condition the memory cells and improve word line setting in advance. This preliminary action ensures that when the actual read operation occurs, the voltage levels are already optimized for reliable detection, thereby improving reliability without significantly extending the critical path operation time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses two distinct under-drive voltage levels to quickly transition through different detection phases. The first under-drive voltage level is applied briefly for initial detection, and the second under-drive voltage level is applied for verify operations. This approach allows the system to rush through the under-drive operation phases efficiently, minimizing the total duration while maintaining reliable word line setting through the use of optimized voltage levels.

Inventive Principle:

Principle #21Skipping (Rushing through)

Data Source

PatentUS20250117155A1Memory device for performing under-drive operation and method of operating the same

Publication Date: 2025.04.10 SK HYNIX INC

AI summary

Provided herein are a memory device and a method of operating the memory device. The memory device may include a memory cell array including a plurality of memory cells coupled to a selected word line, a voltage generator configured to generate an operating voltage that is used for an internal operation, a row decoder configured to perform an under-drive operation including decreasing a voltage level of the selected word line and to apply the operating voltage to the selected word line, and control logic configured to control the row decoder to apply a ground voltage to the selected word line during the under-drive operation.