Enabling Noise Measurements on Magnetic Sensors

Application Notes

Magnetic sensors are used in numerous applications requiring high sensitivity, ranging from brain function mapping to magnetic anomaly detection, magnetic compassing and mineral prospecting. Magnetic sensor sensitivity may be thought of as a signal-to-noise ratio, where the signal is reflected by the gain and the noise is indicated by the inherent noise of the sensor. Sensor manufacturers must characterize and track the inherent 1/f sensor noise, as this is a critical parameter typically represented in nT/√Hz. A new type of magnetic sensor has recently demonstrated higher sensitivity than the standard magnetoresistive sensors, presenting a new noise measurement challenge. Many noise sources may corrupt this measurement, including ambient magnetic field noise, supply noise, and the additive noise from the signal conditioning circuitry. Tunnel magnetoresistance (TMR) sensors offer better resolution, decreased power consumption, and smaller size than their Hall effect, anisotropic magnetoresistance (AMR) and giant magnetoresistance (GMR) counterparts2. Thanks to new innovations in noise measurement hardware and software, accurate measurement of low noise levels in TMR sensors is now possible.