1 Introduction

Achieving the highest precision angle measurements in magnetically sensed applications requires consideration of all possible error sources. These various sources may be the result of mechanical imperfections of the system, or may be related to the signal chain of the sensing device. Taking appropriate design steps in consideration of these factors will help produce the highest accuracy result.

Figure 1-1 Ideal Sine Cosine Arctangent Inputs

Angle is typically measured using sinusoidal inputs 90 degrees out of phase. This sine/cosine relationship allows the use of the arctangent to calculate the final error. This can be achieved using two one dimensional sensors strategically placed with a 90 degree separation about the rotating magnet, or a two or three dimensional sensor can be placed anywhere the magnetic field is sufficiently strong. The separate components of the magnetic field vector is naturally 90 degrees out of phase, which makes these sensors designed for angle detection.