A rotation angle detection system comprises a magnet arranged to rotate around a rotation axis. A first magnetic detection circuit defines a first surface provided with a first and second pairs of magnetic detection elements. A signal processing unit is configured to output a signal representative of a rotation angle of the magnet based on outputs of the first and second pair of magnetic detection elements. A second magnetic detection circuit is provided with another first and second pairs of magnetic detection elements. The signal processing unit is configured to output a redundant signal corresponding to a rotation angle of the magnet based on outputs of the other first pair of magnetic detection elements and the other second pair of magnetic detection elements.