A position sensor arrangement, comprising: a magnetic source and a position sensor device movably arranged relative to each other; the latter comprising at least three magnetic sensors for measuring said magnetic field; a processing unit for determining a position based on a ratio of a first pairwise difference and a second pairwise difference, the first pairwise difference being a difference of a first pair of two signals, the second pairwise difference signal being a difference of a second pair of two signals. A method of determining a position, by performing said measurements, and by calculating said differences and said ratio. A method of calibrating said position sensor, including the step of storing at least one parameter or a look-up table in a non-volatile memory. A method of auto-calibration.