Push-Pull Bridge Magnetic Sensor With Flux Concentrators
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Solution Overview
Problem
Existing push-pull bridge magnetic sensors have insufficient sensitivity and high noise levels, which limits their effectiveness in accurately measuring magnetic fields.
Innovation Solution
The design incorporates soft ferromagnetic alloy flux concentrators aligned along specific axes on push- and pull-arms, with magnetoresistive sense elements placed between them, forming a bridge structure that enhances magnetic field sensitivity and reduces noise through improved linearity and temperature compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing push-pull bridge magnetic sensor structures are used, then temperature compensation function is achieved, but sensitivity is insufficient and noise is high
Solution Approach 1:
The magnetic sensor is divided into push-arm and pull-arm with separate flux concentrators and magnetoresistive sense elements on each arm. This segmentation allows independent optimization of each arm's magnetic field concentration and sensing characteristics, improving overall sensitivity while enabling differential measurement to reduce noise
Solution Approach 2:
Magnetically-soft ferromagnetic flux concentrators are introduced as intermediary elements between the external magnetic field and the magnetoresistive sense elements. These flux concentrators concentrate and guide magnetic flux lines to the sensing elements, significantly enhancing the magnetic field strength at the sensing location and thereby improving sensitivity without introducing additional noise
2Measurement precision
If magnetoresistive sense elements are placed in gaps between flux concentrators, then magnetic field concentration is improved, but manufacturing complexity increases
Solution Approach 1:
The flux concentrators serve multiple functions: they concentrate magnetic flux, provide structural support for positioning sense elements in gaps, and establish defined magnetic field regions. This multi-functionality improves linearity while avoiding additional manufacturing steps that would increase complexity
Solution Approach 2:
The magnetization directions of pinning layers are precisely controlled with opposite orientations on push-arm and pull-arm substrates. This parameter change in magnetization orientation optimizes the magnetic field response and linearity of the sense elements without requiring complex manufacturing processes
3Reliability
If opposite magnetization directions are used on push-arm and pull-arm substrates, then temperature compensation is enhanced, but device complexity increases
Solution Approach 1:
Opposite magnetization directions are deliberately introduced as an asymmetric configuration between push-arm and pull-arm substrates. This asymmetry creates differential temperature responses that cancel out temperature drift effects, enhancing temperature compensation while the symmetric overall structure keeps manufacturing manageable
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 high sensitivity, low noise, and better linearity by concentrating magnetic fields and optimizing the placement of magnetoresistive sense elements, resulting in enhanced performance compared to prior art.
Implementation Method 1
the push-arm flux concentrators and the pull-arm flux concentrators are composed of a material which is a soft ferromagnetic alloy, the magnetically-soft ferromagnetic alloy containing one or more elements of Ni, Fe and Co
Implementation Method 2
magnetically-soft ferromagnetic flux concentrators which are located in gaps between magnetoresistive sense elements and adjacent flux concentrators
Implementation Method 3
Tunneling magnetoresistive (TMR) magnetic sensors are novel magnetoresistance effect sensors which have been industrially applied in recent years, utilize a tunneling magnetoresistance effect of a magnetic multilayer film material to sense magnetic fields
Implementation Method 4
magnetization directions (100) of magnetic pinning layers of the magnetoresistive sense elements on the push-arm substrate are the same, and magnetization directions (101) of magnetic pinning layers of the magnetoresistive sense elements on the pull-arm substrate are the same; and the magnetization directions of the magnetic pinning layers of the magnetoresistive sense elements on the push-arm substrate are opposite to the magnetization directions of the magnetic pinning layers of the magnetoresistive sense elements on the pull-arm substrate
Data Source
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Figure 5~6
AI summary
A high sensitivity push-pull bridge magnetic sensor, wherein the sensor comprises two substrates (20, 21), magnetoresistive sense elements (22, 42), push-arm flux concentrators (23), and pull-arm flux concentrators (41), wherein the magnetization directions of the pinning layers of the magnetoresistive sense elements (22, 42) on the same substrate (20, 21) are the same, but are opposite to the magnetization directions of the pinning layers of the magnetoresistive sense elements (22, 42) on the adjacent substrate (20, 21), and the magnetoresistive sense elements (22) on one substrate (20) are electrically interconnected to form a push-arm of the bridge, and the magnetoresistive sense elements (42) on the other substrate (21) are electrically interconnected to form a pull-arm of the bridge. The magnetoresistive sense elements (22, 42) on the push-arm and pull-arm are aligned respectively in the gaps between two adjacent push-arm flux concentrators (23) and two adjacent pull-arm flux concentrators (41). This sensor can be implemented as a quasi-bridge structure, a half-bridge structure, or a full-bridge structure. The sensor has the advantages of small offset, high sensitivity, excellent linearity, and low noise.