A highly sensitive CMOS digital Hall sensor for low magnetic field applications

Area of Science:

• Electrical Engineering
• Solid-State Physics
• Sensor Technology

Background:

• Integrated CMOS Hall sensors are crucial for magnetic field measurement but suffer from low sensitivity and offset issues in low-field environments.
• Existing Hall sensor technologies face limitations in accurately detecting weak magnetic signals, hindering applications requiring high precision.

Purpose of the Study:

• To develop a highly sensitive digital Hall sensor using 0.18 μm high voltage CMOS technology for effective low magnetic field applications.
• To address the limitations of conventional Hall sensors by improving sensitivity and eliminating offset and noise.

Main Methods:

• Fabrication of a novel digital Hall sensor incorporating a switched cross-shaped Hall plate and a unique signal conditioner.
• Implementation of a dynamic quadrature offset cancellation technique to mitigate offset and low-frequency 1/f noise.
• Characterization of the sensor's performance, including sensitivity and minimum detectable magnetic field.

Main Results:

• The optimized Hall plate achieved a high current-related sensitivity of approximately 310 V/AT.
• The developed digital Hall sensor demonstrated the capability to measure magnetic fields as low as ± 2 mT.
• The sensor maintained reliable digital Hall signal output across a wide temperature range (-40 °C to 120 °C).

Conclusions:

• The novel digital Hall sensor offers a significant advancement for low magnetic field applications due to its high sensitivity and effective noise/offset cancellation.
• The sensor's performance, particularly its ability to detect weak magnetic fields and operate over a broad temperature range, makes it suitable for demanding applications.
• This research contributes a robust solution for precise magnetic field sensing in challenging environments.