A low-noise sub-500µW lorentz force based integrated magnetic field sensing system

Abstract

This paper shows, for the first time, a complete magnetic field sensing system including a Lorentz-force sensor operating out of resonance coupled to an integrated circuit for sensing and actuating the device. Working out of resonance, the trade-off between maximum sensing bandwidth and minimum detectable magnetic field is overwhelmed, improving the resolution and enlarging the bandwidth. However, the reduction of signal amplitude makes the readout electronics a critical block. Measurements carried-out on the whole system show an achievable resolution of 180 nT·mA/√Hz over a 150-Hz bandwidth and an overall power consumption of 460 μW. The integrated readout circuit low-noise performance does not limit the resolution, which is set by the MEMS thermomechanical noise.