Multilayer anisotropic magnetoresistive angle sensor

A multilayer anisotropic magnetoresistive (AMR) sensing stack has been proposed in this paper for high accuracy angle sensing. A quadruple-layer AMR angle sensor was fabricated and showed smaller detection errors than traditional single-layer AMR angle sensors. Based on spectral analysis, intrinsic errors in AMR angle sensors can be attributed to two dominant sources. One is the second harmonic error due to induced anisotropy, and the other is the eighth harmonic error from shape anisotropy. The fabricated quadruple-layer AMR angle sensor with correction algorithm reduces angular errors by a factor of 5 relative to the traditional single-layer device. In addition, the quadruple-layer AMR angle sensor can be operated at low magnetic fields under 100 Oe, enabling the use of weaker, smaller, and cheaper hard magnets for magnetic field sensing. Therefore, the present quadruple-layer AMR angle sensor shows great potential for many industrial applications.