Microsystem for high-accuracy 3-D magnetic-field measurements

A new microsystem for very high-accuracy magnetic measurement of all three field components is presented. A single silicon die incorporating eight sensor devices is mounted on a support and then cut. This galvanic separation is essential, since the applied technology of vertical Hall devices yields very high-quality devices, but does not provide for the isolation. In this way perfect alignment of the sensing directions of the sensors is achieved. All sensors are arranged in such a way that their signals can be combined to represent the x, y and z components of the magnetic flux density in the centre point of the system. The active volume is about 2 mm x 2 mm x 0.2 mm and the precision of the alignment is higher than 0.1 degrees. Measurements of cross-current and cross-sensitivity between the two in-plane axes of an identical but uncut sensor prove the necessity of cutting for achieving an accuracy of better than 1 parts per thousand. (C) 1998 Elsevier Science S.A. All rights reserved.