Single Chip Magnetic Sensor With Interleaved Shielding And Attenuators
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Solution Overview
Problem
Existing magnetic field sensors, such as Hall, AMR, GMR, and TMR sensors, face limitations in sensitivity, power consumption, manufacturing complexity, linearity range, and applicability to high-intensity magnetic fields.
Innovation Solution
A single chip referenced bridge type magnetic field sensor is developed, featuring interleaved magnetoresistive sense and reference element strings, with attenuators and shielding structures to enhance sensitivity and linearity, allowing operation in high-intensity magnetic fields up to 500 gauss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If Hall magnetic field sensors are used, then high-intensity magnetic field operation is enabled, but sensitivity is very low and power consumption is high
Solution Approach 1:
The patent applies different magnetic field manipulation strategies to different spatial locations: sense element strings are positioned in regions with enhanced magnetic field gain while reference element strings are positioned in regions with attenuated magnetic field gain. This local differentiation allows the sensor to maintain high sensitivity through differential measurement while operating in high-intensity magnetic fields.
Solution Approach 2:
The patent changes the magnetic field parameters experienced by different parts of the sensor by introducing magnetic field gain regions and attenuation regions. By spatially varying the magnetic field gain coefficient, the sensor can operate in high-intensity fields while maintaining sensitivity through differential measurement of elements experiencing different field strengths.
2Measurement precision
If TMR magnetic field sensors are used, then sensitivity is higher and power consumption is lower, but linearity range is not wide enough and high-intensity magnetic field applicability is limited
Solution Approach 1:
The patent segments the sensor into multiple sense element strings and reference element strings positioned in different magnetic field environments. This segmentation allows differential measurement that extends the linear range by compensating for saturation effects in high-intensity fields, while maintaining the high sensitivity inherent to TMR elements.
Solution Approach 2:
Different element strings are placed in locations with different magnetic field gain coefficients. Sense elements experience enhanced field gain while reference elements experience attenuated gain, creating local quality differences that enable wide linear range operation while preserving TMR sensitivity.
3Measurement precision
If AMR magnetic field sensors are used, then sensitivity is improved compared to Hall sensors, but manufacturing process becomes complex and power consumption remains high
Solution Approach 1:
The patent uses TMR elements that can function as both high-sensitivity magnetoresistive sensors and are compatible with standard semiconductor manufacturing processes. This universal approach achieves AMR-level sensitivity improvement while avoiding AMR's manufacturing complexity and high power consumption.
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 sensor achieves low power consumption, good linearity, and a wide working range, making it suitable for high-intensity magnetic fields, surpassing the limitations of prior art sensors.
Implementation Method 1
utilizing a tunneling magnetoresistance effect of a magnetic multilayer film material to sense magnetic fields
Implementation Method 2
the sensor comprises at least one attenuator and at least two shielding structures, the attenuator and the shielding structures being mutually interleaved in a spaced manner
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A single chip referenced bridge type magnetic field sensor for high-intensity magnetic field, the sensor comprises a substrate (1), a reference arm, a sense arm, shielding structures (4) and attenuators (5). Wherein the reference arms and the sense arms comprise at least two rows/columns of reference element strings (3) and sense element strings (2) which comprise one or more identical electrically interconnected magnetoresistive sense elements; the reference element strings (3) and the sense element strings (2) are mutually interleaved, each reference element string (3) is designed with a shielding structure (4) on top of it, and each sense element string (2) is designed with an attenuator (5) on top of it. The magnetoresistive sensor elements can be AMR, GMR or TMR sensor elements. The shielding structures (4) and attenuators (5) are arrays of long rectangular bars composed of a soft ferromagnetic material, such as permalloy. The sensor may be implemented in three different bridge structures, a quasi-bridge, a referenced half-bridge, and a referenced full-bridge. This sensor has several advantages including low power consumption, excellent linearity, and wide working range making it able to operate in high-intensity magnetic fields.