Magnetic Memory Bias Structure for Low Power Switching

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Solution Overview

Problem

Conventional MRAMs face issues with high power consumption and reliability due to high currents required for switching at smaller sizes, and performance is affected by initial conditions and size-related issues such as non-uniform switching currents and edge effects, making them unsuitable for higher densities.

Innovation Solution

A magnetic memory system that includes a plurality of magnetic storage cells with a bias structure providing a magnetic bias field greater than zero degrees and less than 180 degrees from the easy axis, which reduces switching current and improves thermal stability, consistency, and reduces magnetic coupling and external disturbances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If current-based switching is used to reduce switching current, then power consumption decreases, but thermal stability and switching consistency are degraded due to initial conditions and edge effects

Engineering Contradiction:

Improvepower consumptionVSAvoidswitching consistency

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

A bias structure is introduced as an intermediary magnetic field source between the current and the magnetic storage element. This bias structure provides a controlled magnetic field that mediates the switching process, ensuring consistent initial conditions and reducing edge effects while maintaining low power consumption through current-based switching

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies parameter changes by controlling the magnetic field parameters (strength, direction, and timing) through the bias structure. By adjusting these magnetic field parameters, the system achieves consistent switching behavior and improved thermal stability while maintaining low power consumption

Inventive Principle:

Principle #35Parameter changes

2Reliability

If magnetic field switching is used to achieve reliable switching, then switching consistency improves, but power consumption increases due to high currents required

Engineering Contradiction:

Improveswitching consistencyVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The magnetic field generation is segmented into two parts: a bias structure that provides a controlled background field and a write line that provides the switching field. This segmentation allows the system to achieve reliable switching with lower total current by combining a static bias field with a smaller dynamic switching field

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The bias structure establishes preliminary magnetic field conditions before the write current is applied. This preliminary action prepares the magnetic storage element for switching, reducing the additional current needed from the write line while maintaining switching reliability

Inventive Principle:

Principle #10Preliminary action

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

The system achieves lower switching currents, more consistent switching, reduced magnetic coupling, and improved thermal stability, making it suitable for higher density memory applications.

Implementation Method 1

The at least one bias structure provides a magnetic bias field in a direction greater than zero degrees and less than one hundred eighty degrees from the easy axis of the magnetic element

Methodology Applied

Scientific EffectMagnetic field: Magnetic Field

Implementation Method 2

Each of the plurality of magnetic storage cells includes at least one magnetic element having an easy axis and being programmable by at least one write current driven through the magnetic element

Methodology Applied

Scientific EffectSpin transfer effect:

Data Source

PatentUS7738287B2Method and system for providing field biased magnetic memory devices

Publication Date: 2010.06.15 RENESAS ELECTRONICS CORP

AI summary

A method and system for providing a magnetic memory is disclosed. The method and system include providing a plurality of magnetic storage cells in an array, a plurality of bit lines, and at least one bias structure. Each of the plurality of magnetic storage cells includes at least one magnetic element having an easy axis and being programmable by at least one write current driven through the magnetic element. The plurality of bit lines corresponds to the plurality of magnetic storage cells. The at least one bias structure is magnetically coupled with the at least one magnetic element in each of the plurality of magnetic storage cells. The at least one bias structure provides a bias field in a direction greater than zero degrees and less than one hundred eighty degrees from the easy axis.