High Frequency Magnetoelectric MEMS-CMOS Oscillator

This paper demonstrates a miniaturized and high resolution (16 nT/Hz$^{1/2}$ ) magnetometer based on a high frequency (168.1 MHz) magnetoelectric Microelectromechanical Systems-Complementary metal-oxide- semiconductor (MEMS-CMOS) oscillator. For the first time, a high frequency and high electromechanical performance (quality factor, $Q~sim ~1084$ and electromechanical coupling coefficient, $k_{t}^{2}~sim ~1.18$ %) magnetoelectric micromechanical resonator based on a self-biased aluminum nitride/iron-gallium-boron (AlN/FeGaB) bilayer nanoplate (250/250 nm) is implemented and used to synthesize a low noise frequency source (2.7 Hz/Hz$^{1/2}$ ) whose output frequency is highly sensitive to external magnetic field (169 Hz/ $mu $ T at zero magnetic field bias).

The angular sensitivity of the magnetometer for electronic compass applications is also investigated showing an ultrahigh angular resolution of 0.34° for a 10- $mu $ T conservative estimate of the earth’s magnetic field, due to the strongly anisotropic sensitivity of the self-biased AlN/FeGaB magnetoelectric resonator. This paper represents the first demonstration of a high resolution self-biased MEMS magnetoelectric resonant sensor interfaced to a compact and low power self-sustained CMOS oscillator as direct frequency readout for the implementation of miniaturized and low power magnetometers with detection limit pushed in $sim 10$ s nT/Hz $^{1/2}$- range. [2014-0086]