A Monolithic 3D Magnetic Sensor in 65nm CMOS with <10μTrms Noise and 14.8μW Power

Abstract

Magnetic sensors have become increasingly ubiquitous as they constitute an integral part of several fast-growing sectors such as automotive, navigation, robotics, medical devices and consumer electronics. Due to their compatibility with the standard CMOS process, Hall magnetic sensors are widely used. However, one of the key challenges of CMOS-based Hall sensors is their relatively low sensitivity, which is inevitable given the low Hall coefficient of Si. For better sensitivity, Hall sensors are biased at higher current levels which hinders their widescale use in low-power bioelectronics and other power-constrained applications. Another challenge is the difficulty in implementing high-sensitivity vertical Hall elements in planar CMOS processes for 3D sensing. This is often overcome by using ferromagnetic materials that require additional and expensive steps during fabrication, thus increasing the cost.

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