Electronic Noise Measurement of a Magnetoresistive Sensor: A Comparative Study

Area of Science:

• Physics
• Electrical Engineering
• Materials Science

Background:

• Giant magnetoresistive (GMR) sensors exhibit significant intrinsic noise at low frequencies, limiting their resolution.
• Accurate GMR noise investigation necessitates measurement systems with noise levels lower than the sensor itself.

Purpose of the Study:

• To evaluate the effectiveness of two electronic noise measurement configurations for a single GMR sensing element.
• To compare noise reduction achieved using different amplification setups and cross-correlation techniques.

Main Methods:

• GMR sensor noise was measured using voltage divider and Wheatstone bridge configurations.
• Three amplifier types (low-noise, ultra-low-noise, instrumentation) were employed.
• Cross-correlation was utilized to mitigate amplifier-induced noise.

Main Results:

• Noise spectra were recorded from 0.5 Hz to 10 kHz at room temperature.
• Sensor detectivity was determined to be in the range of 200-300 nT/√Hz.
• Consistent results across all measurement setups validated their effectiveness.

Conclusions:

• Both voltage divider and Wheatstone bridge configurations, coupled with advanced amplification and cross-correlation, are effective for GMR sensor noise measurement.
• The validated methods enable accurate characterization of GMR sensor noise and detectivity.