FIELD

The present disclosure relates generally magnetic sensors, and, more particularly, to a magnetic sensor with an asymmetric Wheatstone bridge.

BACKGROUND

In the field of speed sensing, a sinusoidal-like signal may be generated by a magnetic sensor in response to a rotation of a target object, such as a wheel, camshaft, crankshaft, or the like. For example, a back bias magnet may be used to produce a magnetic field, and a magnetic speed sensor may be placed between the target object and the back bias magnet. The sinusoidal signal may be generated and translated into pulses, which is further translated into a movement detection or a speed output.

One or more sensor arrangements may be used in a Wheatstone bridge configuration. However, in back bias applications, when a magnetic sensor is placed between a toothed wheel and a magnet, the magnetic field of a standard low cost magnet generates a large static magnetic field to the left side and the right side of the bridge. This large static magnetic field results in a large electrical direct current (DC) offset at the output voltage of the Wheatstone bridge. The electrical DC offset must be compensated by an offset compensation digital-to-analog converter (DAC) or similar solution. A drawback using the offset compensation DAC is that additional noise is introduced into the signal path. This is especially the case if a ratio between the offset and the signal is large, as is usually the case. Then, the offset compensation DAC must be optimized for noise which requires very large chip area.

SUMMARY

Magnetic sensors, sensor modules, and methods thereof are provided.

According to one or more embodiments, a magnetic sensor includes a sensor arrangement including a plurality of magnetic field sensor elements electrically arranged in an asymmetrical bridge circuit, where a first total resistance of a first pair of sensor elements provided on a first side of the asymmetrical bridge circuit is different from a second total resistance of a second pair of sensor elements provided on a second side of the asymmetrical bridge circuit, and the asymmetrical bridge circuit is configured to generate a differential signal based on sensor signals generated by the plurality of magnetic field sensor elements in response to a magnetic field impinging thereon.

According to one or more embodiments, a magnetic sensor module includes a magnet having a magnetic operation point (MOP) and configured to produce a differential magnetic field, the differential magnetic field having a differential MOP field strength at the MOP, and further having a first differential field portion and a second differential field portion. The magnetic sensor module further includes an asymmetric bridge circuit including a plurality of magnetic field sensor elements, including a first pair of sensor elements disposed in the first differential field portion and a second pair of sensor elements disposed in the second differential field portion, where the asymmetric bridge circuit is configured to generate a differential signal based on sensor signals generated by the plurality of magnetic field sensor elements, and the differential signal is zero on a condition that a differential field strength of the differential magnetic field impinging on the plurality of magnetic field sensor elements is equivalent to the differential MOP field strength.

