Dual-mode Arduino-based CMOS-MEMS Magnetic Sensor System with Self-calibration for Smart Buildings’ Energy Monitoring

Abstract

In this paper, a dual-mode Arduino-based CMOS-MEMS magnetic field sensor system (DACM) integrated with on- chip self-calibration is presented. The proposed dual-mode sensor system consists of a micro search-coil magnetometer (µSCM) with a resonance frequency of 1.49 GHz and a micro Hall-effect sensor (HES) using UMC 0.18µm 1P6M CMOS MEMS foundry process. The sensor fusion of HES and µSCM offers both high sensitivity and high sensing range modes. In the high sensitivity mode, the HES and the µSCM can operate independently. This mode is suitable for measuring DC and high-frequency AC magnetic fields and for canceling HES offset, which cannot be achieved using HES alone. In the high sensing range mode, the µSCM is used to cancel the input magnetic field to the HES. According to the measurement results, the high sensitivity mode (open-loop) comes with a sensitivity of 0.767 V/G, and the high sensing range mode (closed-loop) offers a ±15G measurement range. The sensitivity of the µSCM is 7 times larger than the HES at 50 Hz input magnetic field, which will be higher at higher frequencies below the resonance frequency of the µSCM. Furthermore, the µSCM is used for on-chip calibration, suitable for long-term real-time energy & carbon footprint monitoring for smart buildings and smart cities.