Contactless 360 degrees absolute angular CMOS microsystem based on vertical Hall sensors

摘要

We have developed the first 360degrees contactless absolute angular microsystem using a CMOS two-dimensional vertical Hall sensor. The microsystem contains two groups of vertical Hall sensors, mutually oriented at 90degrees, and complete readout electronics. The spinning current method is used to extract the signals from the sensors. Projections onto two orthogonal axes of the external rotating magnetic field give the rotation angle sine and cosine functions, respectively. From these two output signals, the rotation angle is extracted using the four quadrant inverse tangent function without discontinuity or dead angle over 360degrees. An angular accuracy of less than 0.5degrees ( 0.14%) at room temperature with only the Hall sensors' residual offset compensation is obtained. Using gain mismatch and phase compensation, an outstanding accuracy of +/-0.17degrees( +/-0.05%) is achieved. (C) 2004 Elsevier B.V. All rights reserved.