Magnetic Detector Full-Bridge Circuit with Exchange Coupling Bias Films
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Solution Overview
Problem
Current magnetic detectors with full-bridge circuits using magnetoresistive sensors face challenges in achieving high detection accuracy and resistance to strong magnetic fields, particularly in miniaturization and independent bias magnetic field settings for each sensor.
Innovation Solution
The magnetic detector incorporates a full-bridge circuit with two magnetoresistive sensors on the same substrate, each with a pinned magnetic layer and a free magnetic layer, utilizing exchange coupling magnetic fields generated by antiferromagnetic and ferromagnetic layers with different blocking temperatures to set fixed magnetization axes and bias magnetic fields, allowing for independent control and high resistance to strong magnetic fields without external magnetic field application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple magnetoresistive sensors are formed on the same substrate to create a full-bridge circuit, then detection accuracy is improved, but the sensors influence each other through magnetic fields
Solution Approach 1:
The patent divides the magnetic detector into four independent magnetoresistive sensors arranged in a full-bridge circuit configuration. Each sensor is electrically and magnetically isolated through specific structural design, allowing parallel operation without mutual interference while maintaining high detection accuracy through differential measurement.
Solution Approach 2:
The patent applies different magnetic field application directions to different sensors within the full-bridge circuit. Specifically, first and second sensors have bias magnetic fields applied in one direction while third and fourth sensors have bias magnetic fields applied in a perpendicular direction, creating local differentiation that enables accurate magnetic field detection while preventing mutual influence.
2Measurement precision
If independent bias magnetic field control is implemented for each sensor, then detection precision is improved, but device complexity increases
Solution Approach 1:
The patent combines multiple bias magnetic field application functions into a unified structural design. By integrating bias magnetic field application films and utilizing the full-bridge circuit configuration, the system achieves independent control of bias fields for each sensor while sharing common structural elements, thereby reducing overall device complexity.
Solution Approach 2:
The full-bridge circuit structure serves multiple functions simultaneously: it provides differential measurement capability, enables independent bias field control for each sensor, and facilitates temperature compensation. This multi-functionality reduces the need for separate control mechanisms, thereby managing device complexity while maintaining high detection precision.
3Productivity
If sensors are miniaturized to reduce device size, then productivity is improved, but resistance to strong magnetic fields deteriorates
Solution Approach 1:
The patent employs composite magnetic layer structures within each magnetoresistive sensor, combining multiple ferromagnetic layers with different magnetization directions and properties. This composite structure maintains high magnetic field resistance even as the overall sensor size is reduced, enabling miniaturization without sacrificing reliability in strong magnetic field environments.
Solution Approach 2:
The patent implements a nested layer structure within the magnetoresistive sensors, where multiple functional layers (pinned magnetic layers, free magnetic layers, bias magnetic field application films) are stacked vertically. This vertical nesting allows the sensors to maintain complex internal structures for magnetic field resistance while keeping the horizontal footprint small, thereby achieving miniaturization without compromising reliability.
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 configuration enhances the magnetic detector's sensitivity and resistance to strong magnetic fields while enabling miniaturization and precise control over the bias magnetic fields, improving detection accuracy and reducing sensor influence on each other.
Implementation Method 1
utilizing exchange coupling magnetic fields generated by antiferromagnetic and ferromagnetic layers with different blocking temperatures to set fixed magnetization axes
Implementation Method 2
The first magnetic field application bias film is configured to apply a bias magnetic field to the first free magnetic layer
Implementation Method 3
magnetic detectors (magnetic sensors) that include a magnetoresistive sensor with a magnetoresistive film
Data Source
AI summary
A magnetic detector includes a full-bridge circuit including magnetoresistive sensors on the same substrate. The magnetoresistive sensors include two magnetoresistive films and have different relationships between the fixed magnetization direction and the bias application direction. The fixed magnetization direction and the bias application direction are determined with three or more exchange coupling films including antiferromagnetic layers with different blocking temperatures. Thus, the magnetic detector has high resistance to a strong magnetic field, is easy to produce, and has a high degree of flexibility in production.