CONTACTLESS CARD AND CONTACTLESS CARD SYSTEM

• US 20070164122A1
• Filed: 12/07/2006
• Published: 07/19/2007
• Est. Priority Date: 01/17/2006
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ju, Won-Chul
• Application Number:
  US11/567,856
• Publication Number:
  US 20070164122A1
• Time in Patent Office: Days
• US Class Current: 235/492
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0715 the arrangement including means to regulate power transfer to the integrated circuit
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs

Abstract

A contactless card including an antenna coil, a resonant capacitor coupled between both end terminals of the antenna, a plurality of capacitors coupled in parallel with the terminals of the antenna correspondingly through switches, a shunt transistor coupled between the terminals of the antenna, forming a bypassing current path, a rectifier coupled between the terminals of the antenna, generating a DC voltage, and a control circuit sensing the DC voltage and controlling a gate voltage of the shunt transistor and on/off conditions of the switches in accordance with the sensed DC voltage.

Claims

1. A contactless card comprising:

an antenna;

a resonant capacitor coupled between end terminals of the antenna;

a plurality of capacitors coupled in parallel with the end terminals of the antenna through a respective plurality of corresponding switches;

a shunt transistor coupled between the end terminals of the antenna and forming a bypassing current path;

a rectifier coupled between the end terminals of the antenna and generating a DC voltage; and

a control circuit sensing the DC voltage and controlling a gate voltage of the shunt transistor and on/off conditions of the switches in accordance with a level of the sensed DC voltage.

2. The contactless card as set forth in claim 1, further comprising:

a nonvolatile memory supplied with the DC voltage; and

a digital circuit supplied with the DC voltage for processing data to be transceived through the antenna.

3. The contactless card as set forth in claim 2, further comprising:

a demodulator operating to demodulate data received through the antenna; and

a load modulator operating to modulate data to be transmitted by the antenna.

4. The contactless card as set forth in claim 1, wherein the switches comprise NMOS transistors.

5. The contactless card as set forth in claim 1, wherein the control circuit comprises:

a detector determining whether the DC voltage is a predetermined excessive voltage; and

a selector adjusting the gate voltage of the shunt transistor in accordance with a result from the detector and generating selection signals to turn on/off the switches.

6. The contactless card as set forth in claim 1, wherein the shunt transistor comprises an NMOS transistor.

7. A contactless card system comprising:

a contactless card; and

a card reader communicating with the contactless card in a radio mode,

wherein the contactless card comprises;

a nonvolatile circuit generating a DC voltage from data transferred in the radio mode;

a digital circuit controlling the nonvolatile memory and processing data transceived to/from the card reader; and

a control circuit determining whether the DC voltage generated by the analogue circuit is a predetermined excessive voltage,

wherein the analogue circuit comprises;

an antenna;

a resonant capacitor coupled between end terminals of the antenna;

a plurality of capacitors coupled in parallel with the end terminals of the antenna through a respective plurality of corresponding switches;

a shunt transistor coupled between the end terminals of the antenna and forming a bypassing current path; and

a rectifier coupled between the end terminals of the antenna and generating the DC voltage;

wherein the control circuit regulates a gate voltage of the shunt transistor and on/off conditions of the plurality of switches in accordance with a level of the determined DC voltage.

8. The contactless card system as set forth in claim 7, wherein the analogue circuit further comprises:

a demodulator operating to demodulate data received through the antenna; and

a load modulator operating to modulate data to be transmitted.

9. The contactless card system as set forth in claim 8, wherein the control circuit comprises:

a detector determining whether the DC voltage is predetermined the excessive voltage; and

a selector adjusting the gate voltage of the shunt transistor in accordance with a result from the detector and generating selection signals to turn on/off the plurality of switches.