AMR Sensor Without Set/Reset Coil for Stable Magnetic Sensing
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Solution Overview
Problem
Existing AMR sensors require a set/reset coil for biasing, leading to increased power consumption and complexity, and are susceptible to sensitivity loss due to external magnetic interference, with limited linear range and accuracy.
Innovation Solution
An AMR sensor design utilizing an exchange bias layer without a set/reset coil, employing anti-ferromagnetic coupling to stabilize magnetic domains and using barber-pole electrodes at 45° angles for enhanced sensitivity and double-axis operation, along with closely arranged resistor units to eliminate gradient effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a set/reset coil is added to the AMR sensor to restore magnetic domain distribution, then the sensor can work in high-sensitivity mode with improved linearity, but the power consumption increases and the device complexity increases
Solution Approach 1:
The patent extracts and removes the set/reset coil from the AMR sensor structure, eliminating the component responsible for power consumption while maintaining sensitivity through alternative magnetic domain control mechanisms inherent in the AMR material structure
Solution Approach 2:
The AMR sensor utilizes self-service by relying on the intrinsic magnetic properties and hysteresis characteristics of the AMR material to maintain magnetic domain distribution without requiring external set/reset coils, thereby reducing power consumption while preserving measurement precision
2Measurement precision
If a set/reset coil is added to the AMR sensor to restore magnetic domain distribution, then the linearity is improved, but the device complexity increases
Solution Approach 1:
The patent extracts and removes the set/reset coil from the AMR sensor structure, simplifying the device by eliminating additional components and interconnections while maintaining linearity through the inherent properties of the AMR material and optimized electrode configuration
Solution Approach 2:
The AMR material and electrode structure serve multiple functions simultaneously: they provide both the sensing mechanism and the magnetic domain control, eliminating the need for separate set/reset coils and reducing overall device complexity while maintaining measurement precision
3Measurement precision
If externally added permanent magnet is used for bias, then the linearity and stability are improved, but the sensor size is limited and the assembly becomes complex
Solution Approach 1:
The patent merges the bias function with the AMR sensor structure itself by integrating the magnetic bias directly into the sensor layer stack, eliminating the need for separate externally added permanent magnets and reducing assembly complexity while maintaining linearity and stability
Solution Approach 2:
The integrated sensor structure serves multiple functions: it provides both the sensing mechanism and the magnetic bias, eliminating the need for separate bias components and simplifying assembly while maintaining measurement precision
4Device complexity
If permanent magnet film is deposited near magnetoresistive film for bias, then the assembly is simplified, but magnetic domain control becomes difficult and Barkhausen noise is generated
Solution Approach 1:
The patent applies local quality by positioning the biasing magnetic field source directly adjacent to specific regions of the magnetoresistive film where precise magnetic domain control is needed, creating localized magnetic field gradients that enable precise domain control while minimizing Barkhausen noise through optimized local field distribution
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
Reduces power consumption, simplifies manufacturing, enhances sensitivity and accuracy, and allows simultaneous multi-directional magnetic field measurement without gradient errors.
Implementation Method 1
An anisotropy magnetoresistance (AMR) effect refers to a phenomenon that the specific resistance in a ferromagnetic material changes as an included angle between a magnetization intensity of the ferromagnetic material and a current direction changes.
Implementation Method 2
the exchange coupling characteristic of an anti-ferromagnetic layer is used and a reset and set device is not necessary
Implementation Method 3
The magnetoresistive device adopts a Barber-pole electrode structure to improve the sensitivity in a weak magnetic field and expand the linear operating range
Data Source
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AI summary
The present invention comprises an anisotropic magnetoresistive (AMR) sensor without a set and reset device (100) comprising a substrate (140), an exchange bias layer (130), an AMR layer (110) and a collection of barber-pole electrodes (122). An exchange bias layer (130) is deposited on the substrate (140), and an AMR layer (110) is deposited on the exchange bias layer (130). The AMR layer (110) is composed of multiple groups of AMR strips, wherein each group of AMR strips is composed of several AMR strips. The barber-pole electrodes (122) are arranged on each AMR strip under certain rules. The AMR sensor (100) achieves coupling by using the exchange bias layer (130), without requiring a reset/set coil. Because a coil is not be used, the power consumption of the chip is reduced greatly, and the manufacturing process is simpler, providing improved yield and lower cost.