An Integrated Linear CMOS Hall Sensor for 3-D Magnetic Field Measurement With Low-Noise Readout Circuit

This article presents an integrated 3-D Hall sensor with a low-noise analog front end to measure the three-axis linear magnetic field in space. The 3-D Hall device employs a modular design approach, where horizontal and vertical Hall devices (VHDs) are optimized independently, resulting in Hall devices with nearly identical current-related sensitivities (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{I}$ </tex-math></inline-formula>) across all three axes. A shared low-noise analog front end using switching timings for multiplexing is proposed to, furthermore, reduce hardware overhead, which ensures the same accuracy of triaxial signal amplification. The 3-D Hall sensor, prototyped in a 0.18-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula> m CMOS-compatible process, occupies a core area of 0.22 mm2 and draws 4.6 mA from a 1.8-V supply. The experimental results demonstrate that the 3-D Hall sensor prototype exhibits a linearity of greater than 99% over a magnetic field range of ±200 mT; furthermore, the prototype obtains a residual offset of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$120~\mu $ </tex-math></inline-formula> T and a magnetic field resolution of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$146~\mu $ </tex-math></inline-formula> T at a 3-dB bandwidth of 27 kHz.