| 摘要 |
PROBLEM TO BE SOLVED: To obtain a receiving circuit for a noncontact IC card system by which a traffic sensitivity in a whole IC card system is improved by enhancing the detection sensitivity of a receiver in an interrogator. SOLUTION: The receiving circuit is the one for the interrogator 12 of the noncontact type IC card system 50 for exchanging signals by an electromagnetic coupling system between the interrogator 12 and a responder 20 and is also the one for the noncontact type IC card system 50 provided with a first antenna coil 26, a detection transformer 28 where a first winding wire 28a is intervened between the first antenna coil 26 and an antenna coil driving part 24 and a first demodulating part 54 for demodulating the response signal of the responder 20 in carrier wave which is outputted by the interrogator 12 from the secondary winding wire 28b of the detecting transformer 28. In this case, the both ends of the secondary winding wire 28b of the detecting transformer 28 are opened. |
