A global positioning system and integrated circuit with a differential oscillator and with a starting circuit connected to the differential oscillator, wherein the differential oscillator has a current mirror for setting an operating current through each of the two branches, the starting circuit has at least one switch connected to the current mirror, and has a starting means connected to the at least one switch, and the current mirror, the at least one switch, and the starting means are wired in such a manner that the operating current in each of the two branches of the differential oscillator is increased during a starting phase, which phase is a function of the starting means.