Driver Circuit for Simultaneous Set and Reset Voltage Application in Memory Arrays

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Solution Overview

Problem

Semiconductor devices with variable state materials, such as RRAM cells, face challenges in achieving faster and more reliable performance due to longer program times compared to other storage technologies like flash memory.

Innovation Solution

A memory device design that includes a driver circuit capable of providing set and reset voltages simultaneously to different memory cells, utilizing a variable state material between electrodes, allowing for efficient switching between high and low resistance states, and incorporating selection circuitry for selective voltage application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If variable state materials are used in memory cells, then memory cells can be configured with small form factor and non-volatile storage, but program times become longer compared to other storage technologies

Engineering Contradiction:
Improveform factorVSAvoidprogram time
Core Design Contradiction:
Volume of moving objectVSDuration of action of moving object

Solution Approach 1:

The memory array is divided into multiple banks that can be operated independently and concurrently. Each bank can receive set or reset voltages simultaneously, allowing parallel programming operations across different segments of the memory array, thereby reducing overall program time while maintaining the small form factor benefits of variable state materials.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The driver circuit is designed to combine multiple voltage output capabilities in a single integrated circuit. The driver can simultaneously provide set voltages to some memory cells and reset voltages to other cells through shared word lines and bit lines, merging multiple operations into a unified circuit that achieves parallel programming without increasing physical footprint.

Inventive Principle:
Principle #5Merging (Combining)

2Device complexity

If set and reset voltages are applied sequentially to memory cells, then circuit design is simpler, but programming speed is reduced

Engineering Contradiction:
Improvecircuit designVSAvoidprogramming speed
Core Design Contradiction:
Device complexityVSSpeed

Solution Approach 1:

The driver circuit employs dynamic voltage switching capabilities where word line select signals and bit line voltages are dynamically adjusted during each programming cycle. This allows the same physical circuit to perform multiple functions - applying set voltages to some cells while applying reset voltages to other cells simultaneously - achieving parallel operations without requiring separate dedicated circuits for each operation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The driver circuit changes voltage parameters dynamically during operation. By controlling the polarity and magnitude of voltages applied to word lines and bit lines based on programming requirements, the circuit can switch between providing set voltages and reset voltages to different memory cells within the same operational cycle, enabling concurrent operations without increasing circuit complexity.

Inventive Principle:
Principle #35Parameter changes

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 design reduces data programming operation times by allowing concurrent operations on multiple cells, enhancing performance and reliability, and enabling faster switching between resistance states, thereby improving overall memory device efficiency.

Implementation Method 1

a variable state material whose state can be changed from a high resistance state to a low resistance state and back again

Methodology Applied
Scientific EffectResistive switching: Electrical Resistance

Data Source

PatentEP2837000B1Apparatuses and methods for providing set and reset voltages at the same time
Publication Date: 2020.03.25 MICRON TECHNOLOGY INC
  • EP2837000B1 patent drawingFigure 1~2
  • EP2837000B1 patent drawingFigure 3
  • EP2837000B1 patent drawingFigure 4

AI summary

Apparatuses and methods are described, such as those involving driver circuits that are configured to provide reset and set voltages to different variable state material memory cells in an array at the same time. Additional apparatuses, and methods are described.