Position sensor

A low cost x-y digitising system is described for use in consumer electronic devices, such as portable digital assistants, mobile telephones, web browsers and the like. The digitizer includes a resonant stylus, an excitation winding for energising the resonant stylus and a set of sensor windings for sensing the signal generated by the stylus, from which the x-y position of the stylus is determined. The excitation signals applied to the excitation winding are designed to reduce the power drawn from the power supply which makes the digitising system particularly suited to battery operation.