Rasmus Rettig

Giant Magneto Resistors - Sensor Technology and Automotive Applications

The paper will give an introduction to the principle of the giant magneto resistive - GMR - effect and the silicon system integration of GMR sensors. The two main applications of a GMR as a magnetic field strength sensor and as an angular field direction sensor will be discussed under consideration of automotive requirements. The typical applications of a magnetic field strength GMR sensor in incremental position and speed sensing and those of GMR angular field sensors in position sensing will be summarized. Finally advantages of GMR in those applications will be discussed and conclusions on the use of GMR in automotive sensing will be drawn.

Performance of GMR-Elements in Sensors for Automotive Application

In the paper an introduction to the principle of the GMR-effect, and investigations into three types of GMR sensor are presented. Attention is hereby directed to the automotive applications ABS/ESP, engine management systems and transmission control. A sensitive GMR element with an integrated circuit has been developed fulfilling all requirements of the automotive environment for incremental speed sensors. The measurements of the sensors were performed using both active (magnetic) and passive (steel) impulse wheels in a temperature range of -40°C to 170°C. In addition to these investigations, simulations of the magnetic field have been performed to define the magnetic circuit. In order to be able to quantify a direct system advantage, the functionality is discussed compared to products in mass production based on Hall and AMR technology.