TMR Sensor Layout for Sensitivity Drift Compensation
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Solution Overview
Problem
Present-day TMR sensors exhibit high drift in sensitivity due to exposure to high temperatures and mechanical loads, necessitating a need for layouts that reduce or cancel this drift.
Innovation Solution
A magnetic sensor device comprising series-connected TMR resistance elements with varying current flow directions relative to the reference magnetization, allowing for balanced or compensated drifts, thereby reducing overall sensitivity drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If TMR sensors are exposed to high temperatures and mechanical loads, then the sensor can operate in harsh environments, but the sensitivity drift increases significantly
Solution Approach 1:
The sensor device is divided into multiple TMR resistance elements (at least two) with different current flow directions relative to the reference magnetization. Each element experiences different drift characteristics under thermal and mechanical stress, and their combined output compensates for individual drifts, reducing overall sensitivity drift while maintaining operation in harsh environments
Solution Approach 2:
The invention changes the parameter of current flow direction relative to reference magnetization across different TMR elements. By configuring elements with different angular relationships (e.g., parallel, perpendicular, or other angles) between current flow and reference magnetization, the sensor exploits directional sensitivity differences to compensate for temperature- and stress-induced drift through signal combination
2Measurement precision
If TMR resistance elements are arranged with different current flow directions relative to reference magnetization, then sensitivity drift is compensated, but device complexity increases
Solution Approach 1:
The sensor is segmented into multiple TMR resistance elements with different current flow orientations. This segmentation enables drift compensation through diverse directional responses, and the elements can be integrated into a unified sensor structure that processes their combined output, achieving precision improvement without proportionally increasing overall system complexity
Solution Approach 2:
Multiple TMR resistance elements with different current flow directions are merged into a single sensor device with a shared reference magnetization and combined output. The elements work together in a coordinated manner, sharing common structures (substrate, reference layer) while maintaining individual directional characteristics, thus achieving drift compensation without linearly increasing device complexity
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 solution achieves a smaller overall drift in sensitivity by balancing different drifts of TMR resistance elements, resulting in a more robust sensor performance under varying mechanical and thermal conditions.
Implementation Method 1
Tunnel magnetoresistance (TMR) is a magnetoresistive effect that occurs in a magnetic tunnel junction (MTJ), a component which consists of two ferromagnets separated by a thin insulator. If the insulating layer is thin enough (typically a few nanometers), electrons can tunnel from one ferromagnet into the other.
Implementation Method 2
Present-day TMR sensors have a high drift of their sensitivity and thus of the sensor signal if they are exposed to high temperatures and/or mechanical loads.
Data Source
AI summary
The present disclosure relates to a magnetic sensor device, including a substrate spanning a plane, a plurality of series-connected TMR resistance elements arranged on the substrate, wherein each of the TMR resistance elements has at least one magnetic tunnel contact and wherein each of the TMR resistance elements has the same reference magnetization. The series-connected TMR resistance elements are arranged and interconnected on the substrate in such a way that an electric current flow direction in the plane relative to the reference magnetization changes at least once along a current path through the series-connected TMR resistance elements.