MAGNETIC FIELD SENSOR WITH AN ADJUSTABLE THRESHOLD FOR STRAY FIELD IMMUNITY

A magnetic field sensor for detecting motion of an object includes one or more magnetic field sensing elements configured to generate a magnetic field signal in response to a magnetic field associated with the object and a detector configured to generate a comparison signal having edges occurring in response to a comparison of the magnetic field signal and a threshold signal and occurring at a rate corresponding to a speed of motion of the object. A speed monitor responsive to the comparison signal is configured to generate a speed signal having a value indicative of the speed of motion of the object. A threshold generator having an input coupled to receive the speed signal from the speed monitor and an output coupled to the detector is configured to generate the threshold signal at a first level when the value of the speed signal indicates that the speed of motion of the object is greater than a predetermined speed and at a second level when the value of the speed signal indicates that the speed of motion of the object is less than the predetermined speed.