| 摘要 |
PROBLEM TO BE SOLVED: To provide a tuning circuit for a responder in a contactless data communication system where connection of a tuning capacitor is not required. SOLUTION: The tuning circuit of the responder of this invention obtains the power of the responder by receiving an electromagnetic wave sent from an interrogator, the responder is activated by this power so as to attain transmission/reception of data between the interrogator and the responder in the contactless data communication system. The responder is provided with an antenna coil formed by a spiral thin wire on a single plane and with spiral coils formed respectively opposite to each other on the single plane at the start and end of the winding of the antenna coil, and a parasitic capacitor produced between the opposed coils and the antenna coil form the tuning circuit and the tuning frequency is tuned to the frequency of the electromagnetic wave. |
