MTJ Magnetoresistive Switch Circuit for Low-Power High-Frequency Sensing
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Solution Overview
Problem
Existing magnetic switch sensors face challenges with high power consumption and low operating frequency, particularly in industrial applications requiring high sensitivity and frequency response.
Innovation Solution
A magnetoresistive sensor switch utilizing a magnetic tunnel junction (MTJ) structure with a biased magnetic moment orientation, integrated with a push-pull half-bridge circuit and digital control systems, to achieve low power consumption and high frequency operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If Hall sensors or AMR sensors are used to achieve magnetic field detection, then the sensor can operate at low frequency with low power consumption, but the operating frequency is limited to a dozen or so Hz
Solution Approach 1:
The patent changes the fundamental sensing mechanism from Hall/AMR effect to magnetic tunnel junction (MTJ) effect, which fundamentally alters the operating parameters. The MTJ structure enables operation at MHz frequencies (100-1000 times higher than conventional sensors) while maintaining microamp-level power consumption, resolving the frequency-power consumption tradeoff
Solution Approach 2:
The patent employs a composite magnetic tunnel junction structure consisting of multiple ferromagnetic layers (pinned layer, free layer), non-magnetic spacer layers, and tunnel barrier layers. This composite structure enables both high-frequency operation and low power consumption by leveraging quantum tunneling effects in the layered configuration
2Speed
If MTJ sensors are used to achieve high frequency operation at MHz level, then the power consumption is reduced to microamps, but the switch point remains in the range of tens of gauss
Solution Approach 1:
The patent divides the magnetic field sensing function into two separate MTJ elements with different magnetic anisotropy orientations. One element responds to magnetic fields in one direction while the other responds to fields in a perpendicular direction, allowing independent optimization of switch points for each axis and improving overall sensing precision
Solution Approach 2:
The patent applies different magnetic layer configurations and anisotropy types (uniaxial vs. cubic) to different MTJ elements within the same sensor. This allows each element to be locally optimized for specific sensing requirements, with switch points tailored to the specific application needs while maintaining high-frequency operation
3Device complexity
If conventional magnetic switch sensors are used, then the structure is simple, but the power consumption is high in both sleep and working states
Solution Approach 1:
The patent implements periodic switching of the MTJ elements between active and standby states. During operation, only one MTJ element is actively driven while the other is in a low-power standby state, reducing average power consumption. The elements periodically swap roles to maintain sensing coverage while minimizing energy consumption in both working and sleep states
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 enables a magnetoresistive sensor switch with reduced power consumption, improved sensitivity, and high frequency response, effectively addressing the limitations of existing sensors by optimizing the MTJ structure and circuit design.
Implementation Method 1
a new type of magnetoresistive sensor utilizing magnetic tunnel junction (MTJ) has found application in industrial fields. These combine magnetic multilayers with the tunneling magnetoresistance effect. The electrical resistance of the magnetic multilayer depends on the magnitude and the orientation of the external magnetic field.
Data Source
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AI summary
Disclosed in the present invention is a low-power magnetoresistive switch sensor, comprising an internal reference voltage circuit, a multiplexer, a magnetoresistive bridge circuit, a comparison circuit, a voltage stabilization circuit, a digital control circuit, and a digital output circuit; one end of the internal reference voltage circuit is grounded while the other end of the internal reference voltage circuit is connected to the output end of the voltage stabilization circuit; the comparison circuit comprises one or more comparators, one end of the comparison circuit is electrically connected with the voltage stabilization circuit while the other end is grounded, the comparison circuit is provided with one or more input ends and one or more output ends, and the one or more output ends of the comparison circuit are electrically connected with one input ends of the digital control circuit; one end of the magnetoresistive bridge circuit is electrically connected with the output end of the voltage stabilization circuit while the other end is grounded, and the output end of the magnetoresistive bridge circuit is electrically connected with one input end of the comparison circuit. The low-power magnetoresistive switch sensor has the advantages of high sensitivity, low power consumption, high frequency response, small size, and excellent thermal characteristics.