Magnetometer Buffer Circuit for High Sensitivity and Low Noise
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Solution Overview
Problem
Current magnetometers face challenges in achieving high sensitivity, low noise, and low power consumption due to limitations in coil pitch, holding capacitance, and current analog detecting circuits, which hinder the increase in sensitivity and noise reduction.
Innovation Solution
Incorporating a Buffer circuit with high impedance on the input side of the pickup coil and a holding capacitance with small capacity, along with an electronic switch and amplifier circuit, to form a digital-like signal detecting circuit that transfers pulse signal voltage with minimal current flow and high frequency stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the coil pitch is made smaller to increase sensitivity, then the sensitivity of the magnetometer is improved, but the resistance of the pickup coil increases exponentially causing larger IR drops that reduce the holding voltage and sensitivity
Solution Approach 1:
The patent introduces a buffer circuit as an intermediary between the pickup coil and the holding capacitance. This buffer circuit has high input impedance to minimize current draw from the coil, and low output impedance to efficiently charge the holding capacitance. The buffer acts as a mediator that transfers the induced voltage without significant current flow, thereby reducing IR drops while maintaining the benefits of fine pitch coils for high sensitivity.
2Object-affected harmful factors
If the capacity of the holding capacitance is increased to reduce noise, then the noise of the magnetometer is reduced, but the holding capacitance cannot make full charge within the short rising time of pulse current causing decreased holding voltage and sensitivity
Solution Approach 1:
The buffer circuit serves as an intermediary that enables the holding capacitance to charge fully even with larger capacity values. The buffer circuit can deliver sufficient current during the pulse rising time to charge larger capacitances, while maintaining the voltage transfer efficiency. This allows the system to use larger holding capacitance (10 pF or more) for noise reduction without sacrificing sensitivity, as the buffer ensures complete charging within the available time.
3Use of energy by moving object
If the current strength supplied to the magnetic wire is decreased to reduce power consumption, then the power consumption is reduced, but the holding capacitance cannot make full charge causing decreased sensitivity
Solution Approach 1:
The buffer circuit acts as an intermediary that decouples the relationship between pulse current strength and holding capacitance charging. The buffer circuit can maintain adequate charging current to larger capacitances even when the overall pulse current is reduced for lower power consumption. This allows the system to operate with lower power consumption while maintaining sensitivity, as the buffer ensures efficient energy transfer to the holding capacitance.
4Measurement precision
If the resistance of the pickup coil increases due to fine pitch coil, then the sensitivity is improved through smaller coil pitch, but the holding voltage decreases due to larger IR drops in the current analog detecting circuit
Solution Approach 1:
The buffer circuit with high input impedance serves as an intermediary that minimizes the current flow through the high-resistance pickup coil. By presenting a high impedance load to the coil, the buffer circuit draws minimal current, thereby reducing IR drops across the coil resistance. This allows the system to maintain high holding voltage despite the increased coil resistance from fine pitch construction, preserving both sensitivity and signal strength.
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
This configuration enhances sensitivity and reduces noise while maintaining low power consumption by allowing increased holding capacitance and minimizing IR drops, achieving improved performance in high-frequency signal transfer.
Implementation Method 1
the basic concept on MI sensor operated by pulse current through the magnetic wire sensitive to the magnetic field is to detect the change of the impedance according to the magnetic field by the means of the voltage (signal voltage) induced in the pickup coil
Implementation Method 2
If a Buffer circuit is assembled between the pickup coil and the holding capacitance in addition to have the holding capacitance with big impedance as well as the pickup coil with big impedance
Data Source
AI summary
The magnetometers possess a detector part with a magnetosensitive material sensitive to the magnetic field and coil surrounding its magnetosensitive material to pick-up the magnetic field, a pulse generator circuit supplies pulse current to the magnetic material, a sample holding circuit including with an electronic switch synchronized with pulse timing for switching on/off and holding capacitance to charge electricity produced by the pickup coil during the switch on period, and an amplifier circuit amplifies the holding capacitance voltage. Magnetometers possess a Buffer circuit connecting the output side of the pickup coil with the input side of the Buffer circuit and connects the output side of the Buffer circuit with the input side of the electronic switch to transfer the pulse signal voltage induced in the pickup coil from the input side to the output side keeping the pulse signal voltage of the outside at the same level as the inside.