Magneto-Impedance Sensor Driven by 400 MHz Logarithmic Amplifier.

Area of Science:

• Materials Science
• Electrical Engineering
• Sensor Technology

Background:

• Thin-film magnetic field sensors offer non-destructive detection of foreign matter and nanoparticles in industrial and medical products.
• High sensitivity is crucial for smart manufacturing systems requiring comprehensive inspection.
• Existing methods for driving high-frequency magneto-impedance (MI) sensors necessitate specialized circuits.

Purpose of the Study:

• To propose a novel logarithmic amplifier for detecting the 400 MHz output signal of a thin-film MI sensor.
• To demonstrate a simple and effective sensor driving circuit for high-frequency MI sensors.
• To enhance the feasibility of using MI sensors for comprehensive product inspection in smart manufacturing.

Main Methods:

• Design and implementation of a compact, integrated circuit (IC) logarithmic amplifier.
• Integration of the logarithmic amplifier with a chip Voltage Controlled Oscillator (VCO) and an MI sensor.
• Characterization of the sensor's performance at approximately 500 MHz.

Main Results:

• The proposed logarithmic amplifier effectively translates hundreds of MHz radio frequency (RF) signals to a proportional direct current (DC) voltage.
• The amplifier is a small IC-chip (approx. 5 mm x 5 mm), suitable for integration into compact devices.
• A simple sensor driving circuit was composed using the chip VCO, MI sensor, and logarithmic amplifier.

Conclusions:

• The developed logarithmic amplifier is a key component for enabling high-frequency MI sensor applications.
• The proposed circuit configuration simplifies the driving of sensitive MI sensors.
• This technology presents a promising candidate for advanced non-destructive inspection in smart manufacturing environments.