US Patent 10274507 Stray-field robust, twist-insensitive magnetic speed sensors

A magnetic sensor module includes a magnetic sensor having an in-plane axis and an out-of-plane axis, and including a differential pair of sensor elements spaced apart from each other. The differential pair of sensor elements are configured to generate measurement values in response to sensing a bias magnetic field. The magnetic sensor module further includes a back bias magnet including two opposing poles, where the back bias magnet is magnetized in a magnetized direction that is parallel to the in-plane axis and generates the bias magnetic field; a first magnetic flux guide disposed at a first pole and configured to redirect a first portion of the bias magnetic field towards the magnetic sensor along the in-plane axis; and a second magnetic flux guide disposed at a second pole and configured to redirect a second portion of the bias magnetic field towards the back bias magnet along the magnetized direction.