A 770 KS/s Duty-Cycled Integrated-Fluxgate Magnetometer For Contactless Current Sensing

This work describes a sampling-rate scalable, package-integrated magnetometer with CMOS-integrated fluxgate, that achieves 100x lower compensation energy with duty cycling for 1kHz power monitoring applications, while achieving 1.67x higher peak BW than previous IFG sensors for fault detection. Key contributions include 1) mixed signal front-end design to hold digitized compensation value during sleep and resume operation from last converged point (LCP), saving up to 100 convergence cycles when duty cycling, 2) hierarchical bypass/coarse/fine search modes to guarantee quick convergence (< 20μs), even for 2mT field swing between samples in heavily-duty-cycled systems, and 3) faster sampling and read out (1.3μs) for lower energy per sample and higher BW.