A Low 1/f Noise Tunnel Magnetoresistance Accelerometer

Aiming at minimizing 1/f noise of tunnel magnetoresistance (TMR) accelerometers, a new principle incorporated acceleration sensing and 1/f noise suppression is demonstrated both theoretically and experimentally. The elasto-magneto-electric conversion theory is analyzed and a linear relationship between input acceleration and output voltage is derived. A new modulation methodology based on periodically biased magnetic field is proposed and validated to effectively minimize 1/f noise of TMR accelerometers, by integrating a high-frequency resonator with a soft magnetic modulation film. A prototype is used to experimentally demonstrate that a sensitivity of 8.2 mV/g can be realized for acceleration sensing and 1/f noise can be minimized by at least 80 times. This work clarifies a universally applicable low noise sensing principle not only for TMR accelerometers but also for all of the elasto-magneto-electric coupling sensors like MR/ME displacement sensors or strain sensors.