Abstract: The invention relates to a contactless and batteryless chip card having an antenna coil, a transmission and reception stage which via an electromagnetic alternating field generated by a write/read unit on the one hand supplies the chip card with energy and on the other hand ensures bidirectional data transmission to the write/read unit. The chip card in accordance with the invention has a detector for determining the field strength of the electromagnetic alternating field transmitting energy to said chip card. The functions of the user part, which have a high energy requirement to implement them, are only implemented advantageously when the detector has detected a sufficient field strength. This prevents defective or incomplete implementation of energy-consuming functions of the chip card before they are begun. The field strength detector consists of a switch and load in parallel to the coil with the switch controlled by a control circuit to cause the switch to be on only during a measurement cycle.

Abstract: The invention relates to a method and a circuit array for regulating the supply voltage of a load as may be found, for example, in the form of an integrated circuit in a chip card. An integrated circuit of this type contains a non-volatile memory and the control logic needed to read out the information stored in the non-volatile memory, but with the transmission of both energy and data being wireless, for example inductive. Data is transmitted by suitable modulation of the voltage supply. In order for the reader to clearly evaluate the read-out logic states, it is proposed in accordance with the invention that during output of the first logic level the supply voltage of the load is generated by serial regulation and that during output of the second logic level the terminal voltage of the voltage source is under parallel regulation.