Patent ID: 7218204

Claim:
A contactless IC card comprising: a coil antenna for receiving electromagnetic wave energy that is transmitted from an external device; and a semiconductor integrated circuit including: a rectifier for rectifying an output signal from said coil antenna to generate a first supply voltage having an RX (received) signal superimposed thereon; a demodulator for extracting the RX signal from the first supply voltage; a digital signal processing unit for signal processing the extracted RX signal; a reference voltage circuit for generating a reference voltage; a judging circuit for judging whether the reference voltage is equal to or higher than a predetermined voltage which has an earlier rising time than the reference voltage; and a power supply voltage stabilization unit for generating a second supply voltage from the first supply voltage on the basis of a result of the judgment by said judging circuit, wherein said power supply voltage stabilization unit is operable to supply the first supply voltage to the second supply voltage when said judging circuit judges that the reference voltage is lower than the predetermined voltage.