System for sensing changes in a magnetic field, and fabrication method.

摘要

All of the resistors in a magnetic field sensitive circuit, both magnetoresistors (MRs)and fixed resistors (FRs), are formed simultaneously in a common fabrication process from a common magnetoresistive material. An additional structure in the form of Hall shorting strips is applied to selected resistors to rendered them MRs, while the resistors without the additional structure function as FRs. In one circuit the resistors are arranged in pairs in two voltage divider circuits. The high voltage resistor from one circuit and the low voltage resistor from the other circuit are MRs while the remaining resistors are FRs, producing an increased magnetic sensitivity. In another circuit all resistors are MRs and are positioned so that the magnetic field at one pair swings in a direction opposite to that of the other pair, further increasing the magnetic sensitivity. Discrepancies stemming from temperature coefficient mismatch and manufacturing variations are substantially reduced. <IMAGE>