The present invention relates in one aspect to an auxiliary charge pump for a RFID rectifier, the charge pump, which comprises a first charge pump stage (11; 111) connected to an input (14; 114), a second charge pump stage (12; 112) connected to the input, a diode clamp (13; 113) connected to an output (15; 115), and a regulating transistor (16; 116) having a gate connected with an output (21; 121) of the first charge pump stage and having a source and a drain, wherein one of the source and the drain is coupled to the diode clamp. In further aspects the invention relates to a RFID transponder, to a multistage rectifier and to a rectifier stage comprising such an auxiliary charge pump.
