A CMOS Hall Sensors Array With Integrated Readout Circuit Resilient to Local Magnetic Interference From Current-Carrying Traces

This article proposes a CMOS Hall sensors array with readout circuitry to counteract the magnetic interference from nearby conductors carrying high currents. The
$3\times $
3 Hall sensors array with current-spinning collects the spatial magnetic field information in a time-interleaved manner while the readout circuitry, formed by a capacitively-coupled instrumentation amplifier (CCIA) with
${T}$
-capacitor feedback network, amplifies the transduced signals for subsequent processing. The calibration mechanism analyzes the magnetic field distribution on the array and separates the magnetic field component due to the environment and local perturbation from adjacent traces, enabling accurate detection of the environmental magnetic field. Prototyped in a 0.35-
$\mu \text{m}$
CMOS process, the Hall sensors array and readout circuit occupy an area of
$2.2\times2.2$
mm
²
and consume 3.5 mA of current under a 3.3-V supply. The hall sensors achieve an average sensitivity of 100 V/(
$\text{A}\cdot \text{T}$
). The input-referred noise (IRN) of the entire circuit is 0.128
$\mu \text{T}/\surd $
Hz. With the interference cancellation scheme, the error in the magnetic field readings caused by a conductor 5 mm from the center of the chip carrying 3 A of current reduced from 120 to 5
$\mu \text{T}$
, corresponding to a
$24\times $
improvement. Overall, the average error of the captured magnetic field after calibration reaches 0.9%.