Indium antimonide magnetoresistors are useful for magnetic position sensors because of their high sensitivity. Doping profiles for these thin film devices have been optimized to improve their thermal stability at elevated operating temperatures and to reduce mismatch between dual magnetoresistors, and more advanced designs incorporate an indium aluminum antimonide buffer layer. These sensors are useful for vehicular applications such as crankshaft and camshaft sensors for engine ignition control. A sensing system has been developed which involves a complementary dual-track ferromagnetic target wheel and a permanent magnet with two indium antimonide magnetoresistors mounted on its surface. This geometry enhances the accuracy and repeatability of the pulses obtained from the magnetoresistors and gives power-on state recognition.
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