Graphene Hall Sensor Gate Voltage Modulation for Noise Reduction
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Solution Overview
Problem
Hall sensors, particularly those using silicon and graphene materials, face limitations in detecting low-frequency magnetic fields due to flicker noise and variability in contact resistance, which restricts their detectable magnetic field range and sensitivity, leading to bandwidth limitations and high noise performance.
Innovation Solution
A graphene Hall sensor system with a control gate for adjustable gate voltage modulation to mitigate flicker and 1/f noise, integrated capacitive contacts for low impedance AC coupling, and adaptive sensitivity control to extend the detectable magnetic field range without restricting sensor bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If graphene Hall sensors are used to provide high magnetic field sensitivity, then magnetic field sensitivity is improved, but contact resistance variability leads to unpredictable noise performance and reliability deteriorates
Solution Approach 1:
The patent introduces a dielectric layer as an intermediary between the graphene Hall sensor and the metal contact electrode. This capacitor structure mediates the interface, providing stable electrical coupling while isolating the graphene from direct contact with the metal, thereby eliminating contact resistance variability and ensuring predictable noise performance while maintaining high sensitivity.
Solution Approach 2:
The patent changes the electrical parameters at the graphene-contact interface by introducing a capacitor structure with controlled capacitance. This parameter change transforms the interface from a resistive contact (with variable resistance) to a capacitive coupling (with stable impedance characteristics), improving reliability while preserving sensitivity.
2Object-affected harmful factors
If spinning current technique is used to address low frequency noise, then flicker noise is reduced, but sensor bandwidth is limited and device complexity increases
Solution Approach 1:
The patent extracts and removes the complex spinning current circuitry from the system. Instead of using active current switching and averaging circuits, the invention achieves noise reduction through passive capacitor filtering that blocks low-frequency noise while allowing high-frequency signals to pass, thereby reducing flicker noise without adding circuit complexity.
Solution Approach 2:
The patent replaces the mechanical/electrical switching mechanism of spinning current technique with a passive electrical filtering mechanism using capacitors. This substitution eliminates the need for switching arrays and control logic, reducing device complexity while maintaining noise reduction effectiveness.
3Reliability
If minimum contact resistance is enforced in graphene Hall sensors, then electrical connection is improved, but noise performance becomes unpredictable and reliability decreases
Solution Approach 1:
The patent introduces a capacitor as an intermediary element between the graphene and metal contact. This capacitor provides stable electrical coupling with predictable impedance characteristics, replacing the unreliable direct ohmic contact. The capacitive interface ensures both reliable electrical connection and predictable noise performance by eliminating contact resistance variability.
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 enhances the sensitivity and noise immunity of Hall sensors, allowing for real-time sensitivity adjustment and improved minimum detectable magnetic field detection, while maintaining low power consumption and reducing noise, thus extending the usable range of Hall sensor technology.
Implementation Method 1
Hall effect sensors are used in magnetometers, current sensors and other applications for sensing or detecting magnetic fields. Many Hall sensors employ silicon-based material for transformation of a magnetic field signal into an electrical signal based on galvanomagnetic effects
Implementation Method 2
Hall sensors typically suffer from flicker noise, particularly at low frequencies
Implementation Method 3
example fabrication techniques and graphene devices have integrated capacitive contacts to facilitate low impedance AC coupling to instrumentation amplifiers or other circuits
Data Source
AI summary
Graphene Hall sensors, magnetic sensor systems and methods for sensing a magnetic field using an adjustable gate voltage to adapt the Hall sensor magnetic field sensitivity according to a control input for environmental or process compensation and/or real-time adaptation for balancing power consumption and minimum detectable field performance. The graphene Hall sensor gate voltage can be modulated and the sensor output signal can be demodulated to combat flicker or other low frequency noise. Also, graphene Hall sensors can be provided with capacitive coupled contacts for reliable low impedance AC coupling to instrumentation amplifiers or other circuits using integral capacitance.