Magnetic Field Sensing via Stress Modulation to Suppress 1/f Noise
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Solution Overview
Problem
Current magnetic field detection devices face challenges in achieving high detection resolution due to limitations in sensitivity and interference from 1/f noise, particularly in detecting weaker magnetic fields.
Innovation Solution
A magnetic field detection device and method that incorporates a modulator to apply stress oscillating at a specific frequency orthogonal to the sensitivity axis of magnetic field detection elements, combined with a demodulator using high-pass filters and phase detection circuits to enhance sensitivity and remove noise, allowing for accurate detection of magnetic field intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an alternating current magnetic field is applied to a giant magneto-resistive effect element, then detection resolution is improved, but 1/f noise interferes with detection of weaker magnetic fields
Solution Approach 1:
The patent applies mechanical stress oscillation to the magnetic field detection element instead of using alternating current magnetic fields. The stress oscillation modulates the magnetic field sensitivity at a specific frequency, allowing the detection element to respond to magnetic fields while avoiding the 1/f noise that plagues conventional AC-based methods. This mechanical vibration approach fundamentally changes how the detection element is stimulated.
Solution Approach 2:
The patent employs periodic stress oscillation at a specific frequency to modulate the magnetic field detection element. By applying stress periodically rather than continuously or randomly, the system can use frequency-based filtering to distinguish the desired signal from 1/f noise. The periodic action creates a characteristic frequency signature that can be easily filtered and detected.
2Measurement precision
If stress oscillation is applied to modulate sensitivity, then detection resolution is improved, but device complexity increases due to modulator and demodulator components
Solution Approach 1:
The patent introduces a modulator as an intermediary component that applies stress oscillation to the magnetic field detection element. This modulator acts as a mediator between the control system and the detection element, enabling frequency-based modulation without requiring complex internal modifications to the detection element itself. The demodulator then serves as a second intermediary to extract the modulated signal, creating a cleaner separation of functions.
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 higher detection resolution and reproducibility by modulating sensitivity through stress application and effectively removing 1/f noise, enabling precise measurement of magnetic fields, even at lower intensities.
Implementation Method 1
a modulator configured to apply, to the magnetic field detection element, a stress oscillating at a first frequency and including a component in a second direction
Implementation Method 2
a magnetic field detection element having a sensitivity axis in a first direction
Data Source
AI summary
A magnetic field detection device includes a magnetic field detection element, a modulator, and a demodulator. The magnetic field detection element has a sensitivity axis in a first direction. The modulator is configured to apply, to the magnetic field detection element, a stress oscillating at a first frequency and including a component in a second direction, the second direction being orthogonal to the first direction. The demodulator is configured to demodulate an output signal having the first frequency and outputted from the magnetic field detection element, and detect, on a basis of an amplitude of the output signal, an intensity of a measurement magnetic field to be received by the magnetic field detection element.