A 0.18-µm CMOS current-mode Hall magnetic sensor with very low bias current and high sensitive front-end

This paper describes a magnetic Hall sensor working in current mode and its electronic interface. The microsystem uses the current spinning technique to compensate for the offset and provides a differential output signal current. The use of a low-noise chopper stabilized operational amplifier enables the integration of the signal current and ensures, after the sensor interface, a voltage sensitivity of 1660 V/A/mT (@ 25 kS/s) with a sensor bias current as low as 12 µA. The current-mode Hall sensor and the analog integrator read-out circuit have been fabricated with a 6-metal 0.18-µm standard CMOS technology. The current spinning technique reduces the offset to less than 50 µT (measured over 10 samples).