Vertical Magnetoresistive Current Sensor for Weak Current Detection
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Solution Overview
Problem
Conventional current sensors using giant magnetoresistive elements face challenges in miniaturization and sensitivity when detecting weak currents due to the placement of GMR elements adjacent to the conductor, which limits their ability to accurately measure low currents and hinders compact design.
Innovation Solution
The current sensor design features a magnetoresistive element and conductor in different layers, with specific dimensional constraints to enhance magnetic field application and reduce heat influence, allowing for high-sensitivity detection of currents between 3 mA and 50 mA, and includes multiple conductors and magnetoresistive elements to create composite magnetic fields for improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the magnetoresistive element is disposed adjacent to the conductor in the same layer, then the device complexity is reduced, but the measurement precision and sensitivity to weak currents deteriorate
Solution Approach 1:
The patent transitions from a planar in-plane arrangement to a three-dimensional vertical stacking configuration. The conductor and magnetoresistive element are positioned in different layers with controlled vertical distance D1, enabling closer proximity and stronger magnetic field coupling without planar complexity, thereby improving sensitivity to weak currents while maintaining structural simplicity.
Solution Approach 2:
The patent optimizes specific geometric parameters including the vertical distance D1 between conductor and magnetoresistive element, and the cross-sectional area S1 of the conductor. By controlling these parameters within specific ranges, the magnetic field strength at the magnetoresistive element is enhanced, improving measurement precision for weak current detection.
2Measurement precision
If the distance between conductor and magnetoresistive element is reduced to improve sensitivity, then the measurement precision improves, but the heat influence from conductor on magnetoresistive element increases
Solution Approach 1:
The patent utilizes vertical layering to achieve close proximity (small D1) for strong magnetic coupling while the lateral offset and layered structure provide thermal management advantages. The magnetoresistive element is positioned at a specific vertical distance from the conductor, allowing efficient magnetic field detection while reducing direct thermal contact and heat interference.
Solution Approach 2:
The patent introduces an insulating film between the conductor and magnetoresistive element. This intermediary layer provides electrical insulation and thermal isolation, reducing heat transfer from the conductor to the magnetoresistive element while still allowing the magnetic field to penetrate and affect the magnetoresistive element's resistance.
3Object-affected harmful factors
If the cross-sectional area of conductor is increased to reduce heat influence, then the heat interference decreases, but the device area increases hindering miniaturization
Solution Approach 1:
The patent moves the relationship between conductor and magnetoresistive element from a planar configuration to a three-dimensional vertical stacking arrangement. This allows the conductor to have sufficient cross-sectional area for heat management while the overall device footprint is minimized through vertical integration rather than lateral expansion.
Solution Approach 2:
The patent employs a nested layered structure where the magnetoresistive element is positioned in a second layer above the conductor in the first layer. This nesting approach allows multiple functional elements to occupy overlapping vertical spaces, reducing the overall device area while maintaining appropriate conductor dimensions for thermal management.
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 enables compact, high-accuracy measurement of weak currents with reduced heat influence and noise interference, enhancing the sensitivity and linearity of current detection.
Implementation Method 1
a first magnetoresistive element which is disposed at an area corresponding to the first extended portion in a second layer, a resistance value of the first magnetoresistive element varying according to a first magnetic field generated by a current flowing through the first extended portion
Data Source
AI summary
A current sensor that is compact can detect with high sensitivity and high accuracy a magnetic field generated by a current. The current sensor has a thin film coil including turn portions extending in an X-axis direction at a second layer, and a first magnetoresistive element which includes element patterns disposed at a first layer in areas corresponding to the turn portions, the resistance value of which varies according to a magnetic field generated by a current detected of from 10 to 50 mA flowing through the turn portions. The distance between each turn portion and each element pattern is from 0.4 to 1.0 μm. Each cross-sectional area at the turn portions is from 0.4 to 3.0 μm2. This permits efficient detection of a magnetic field without the influence of heat generated from the thin film coil.