A RFID transponder includes an electronic circuit and an antenna, the electronic circuit being integrated in a p-type substrate and comprising a modulator formed by a PMOS transistor whose drain, electrically connected to a pad of the antenna, and source, connected to the ground of the electronic circuit, are arranged in an n-type well provided in the p-type substrate. The PMOS transistor has a gate driven by a driving circuit which is arranged for providing at least a negative voltage, this negative voltage being low enough for turning on this PMOS transistor in response to a control signal provided by a logical unit of the electronic circuit.