Patent ID: 6570490
Filing Date: 2003-05-27
Classification: G06K

Abstract:
A contactless IC card comprising:an antenna; a transmit/receive circuit for recovering a data signal and electric power from a carrier signal received by said antenna; a logic circuit operated with said electric power supplied thereto from said transmit/receive circuit; and a memory, wherein said transmit/receive circuit includes a plurality of impedance elements and a plurality of charge pump circuits; said plurality of impedance elements include a first impedance element having one end connected to a ground, a second impedance element having one end connected to the other end of said first impedance element, a third impedance element having one end connected to the other end of said second impedance element, and a fourth impedance element having one end connected to the other end of said third impedance element, said first impedance element having the other end connected to an input terminal of said carrier signal; each said charge pump circuit includes a first diode, a second diode, a flying capacitor having one end connected to a first electrode of said first diode and to a second electrode of said second diode, and a capacitor arranged between a first electrode of said second diode and the ground; a first charge pump circuit which comprises said first diode having a second electrode connected to the ground, said flying capacitor having the other end connected to the other end of said second impedance element, and said second diode having the first electrode thereof connected to an output terminal of said data signal; a second charge pump circuit which comprises said first diode having the second electrode thereof connected to the ground, and said flying capacitor having the other end connected to the other end of said third impedance element; and a third charge pump circuit which comprises said first diode having the second electrode thereof connected to the first electrode of said second diode of said second charge pump circuit, said flying capacitor having the other end connected to the other end of said fourth impedance element, and said second diode having the first electrode thereof connected to an output terminal of said electric power.