Magnetic Sensor Three-Axis Sensing MTJ Orientation
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Solution Overview
Problem
Conventional magnetic field sensors, such as AMR and GMR devices, are limited in their ability to sense multiple axes and often struggle with determining orientation and position, especially at low speeds or when stationary, due to their design and operational limitations.
Innovation Solution
The development of a magnetic sensor using mutual supplement tunneling magneto-resistors (MS-TMRs) with specifically oriented magnetic tunneling junctions and pinned layers, allowing for three-axis magnetic field sensing by varying conductivity in response to external magnetic fields, enabling linear output and improved sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional AMR or GMR magnetic field sensors are used, then the device can sense magnetic fields, but it is limited to two-axis or unipolar mode sensing only
Solution Approach 1:
The patent combines two magnetic tunneling junctions (MTJs) with different magnetization orientations into a single sensor element. The first MTJ has magnetization along the easy axis while the second MTJ has magnetization along the hard axis, allowing the device to sense both in-plane and out-of-plane magnetic field components simultaneously, achieving three-axis sensing capability
Solution Approach 2:
The magnetic sensor is designed to perform multiple sensing functions using a single device structure. By integrating MTJs with different magnetic anisotropy orientations, the sensor can detect magnetic fields along multiple axes (x-axis, y-axis, and z-axis) and determine both orientation and position information, making it universally applicable for various navigational scenarios
2Measurement precision
If conventional GMR sensors are used, then they can detect magnetic field magnitude, but they cannot determine the exact direction of the field
Solution Approach 1:
The patent applies local quality by giving different magnetic properties to different parts of the sensor. The first MTJ is designed with easy-axis magnetization for sensing in-plane fields, while the second MTJ is designed with hard-axis magnetization for sensing out-of-plane fields. This localized differentiation of magnetic characteristics enables precise direction detection without requiring complex external sensing mechanisms
Solution Approach 2:
The invention transitions from two-dimensional in-plane sensing to three-dimensional sensing by incorporating the out-of-plane sensing capability through the hard-axis magnetized MTJ. This adds the z-axis dimension to the traditional x-y plane sensing, enabling full three-axis magnetic field vector detection and precise direction determination
3Measurement precision
If conventional magnetic field sensors are used in GPS systems, then they can provide orientation information, but they cannot provide accurate position sensing when the object stops or travels at low speed
Solution Approach 1:
The patent segments the magnetic sensing function into three independent axis components using separate MTJ elements oriented along different magnetic axes. This segmentation allows the sensor to independently measure magnetic field components along the x-axis, y-axis, and z-axis, providing complete three-axis magnetic field vector information that enables accurate position and orientation determination even at low speeds or when stationary
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 solution enables accurate three-axis magnetic field sensing, improving navigational capabilities in electronic devices like GPS systems by providing precise orientation and position information even at low speeds or when stationary.
Implementation Method 1
a first magnetic tunneling junction and a second magnetic tunneling junction conductively disposed between the first electrode and the second electrode
Implementation Method 2
a first pinned layer having a first pinned magnetization, a first free layer having a first free magnetization
Implementation Method 3
a first free layer having a first free magnetization, and a second free layer having a second free magnetization
Data Source
AI summary
A magnetic sensor for sensing an external magnetic field includes first and second electrodes and first and second magnetic tunneling junctions. The first and second electrodes are disposed over a substrate; and the first and second magnetic tunneling junctions are conductively disposed between the first and second electrodes and connected in parallel between the first and second electrodes. The first and second magnetic tunneling junctions are arranged along a first easy axis of the magnetic sensor. The first magnetic tunneling junction includes a first pinned magnetization and a first free magnetization, and the second magnetic tunneling junction includes a second pinned magnetization and a second free magnetization. The first free magnetization and the second free magnetization are arranged substantially in parallel to the first easy axis and in substantially opposite directions.