What’s the Difference Between TMR and GMR Sensors? (.PDF Download)

June 21, 2017
What’s the Difference Between TMR and GMR Sensors? (.PDF Download)

Demand for magnetic sensors continues to grow across a wide range of applications – from automotive electronics to industrial equipment and consumer electronics. For instance, tunnel-magnetoresistance (TMR) sensors can be used in cars’ steering columns to improve the accuracy of automated parking capabilities. As such, these advances move the automotive industry closer to required instantaneous processing and actions for fully autonomous driving.

Due to these emerging applications, various electronics companies have developed TMR sensors that utilize a new type of magnetic sensor as their main working principle. This new sensor technology often leverages a wealth of technologies built up in the manufacturing of hard-disk-drive (HDD) magnetic heads, but with additional enhancements.

Mass production of TMR sensors has been ongoing since 2014. TMR technology sensors achieve a high output—about 20 times higher than conventional anisotropic magnetoresistance (AMR) sensors, and nearly six times higher than giant magnetoresistance (GMR) sensors, the latter of which contain at least two magnetic layers separated by a nonmagnetic layer. TMR sensors also offer advantages such as high accuracy, high stability with less temperature drift, and less aging deterioration. They also perform well as angle sensors, position sensors, and rotary sensors.

Significantly Higher Output

The TMR element, manufactured using advanced thin-film process technology, is a thin-film element in which the barrier layer of an insulator is sandwiched between two ferromagnetic substance layers (free layer and pin layer). The magnetic orientation of the pin layer is fixed, while the magnetic orientation of the free layer changes in accordance with the direction of the external magnetic field. The electrical resistance of the TMR element changes along with this change in the free layer.


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