Contactless card and contactless card system
OwnerWon-Chul Juinventor
Life of this patent
Estimating the term…
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.
Claims9
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.
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.
Dependencies are inferred from the claim text.