Method and circuit arrangement for determining the direction of an external magnetic field

A circuit arrangement for determining the direction of an exterior magnetic field B, using a magnetoresistive sensor, having the

• means (3) for superimposing a fluctuating magnetic field on the exterior magnetic field B;
• means (1, 4, 5) for generating a first and second signal, dependent on the sine and cosine of an angle of the exterior magnetic field relative to a reference direction;
• eliminating or ignoring any signal components dependent on the fluctuating magnetic field;
• means (8) for ascertaining a third signal, which can be associated with the angle of the exterior magnetic field relative to the reference direction, on the basis of the first and second signal, this third signal having a periodicity of 180°;
• means (10, 11, 16, 17, 18, 19, 20, 21, 12, 13, 14, 24, 25, 26) for ascertaining a correction logical signal K5, taking into account the signal component, eliminated from the first and second signal and dependent on the fluctuating magnetic field, which signal component assumes a first level for an angle of the exterior magnetic field B in a first angle range, in particular between 0 and 180°, and a second level in a second angle range, in particular between 180 and 360°;
• and
• means (30) for ascertaining the actual angle of the magnetic field B on the basis of the logic correction signal K5 and of the third signal.