Signal processing circuit and antenna apparatus

摘要

To form a signal processing circuit and an antenna apparatus that do not need a circuit to adjust resonant frequency of a resonant circuit or resonant-frequency adjustment work and that are downsized, an antenna coil and a capacitor define an antenna resonant circuit. An impedance matching circuit including capacitors, a first coil, and a second coil is provided between the antenna resonant circuit and a wireless IC. The first coil and the second coil are magnetically coupled.

主权项

1. An antenna apparatus, comprising:
a wireless IC configured to be used in a wireless IC device to perform wireless communication with external equipment and including a first input/output terminal and a second input/output terminal; an antenna resonance circuit including an antenna coil configured to transmit and receive a signal by the wireless communication with the external equipment, one end of the antenna coil being connected to the first input/output terminal, and another end of the antenna coil being connected to the second input/output terminal; and an impedance matching circuit including a portion that is connected between the first and second input/output terminals of the wireless IC and the antenna resonance circuit, the portion of the impedance matching circuit including:
a first coil connected between the first input/output terminal and the one end of the antenna coil; anda second coil connected between the second input/output terminal and the another end of the antenna coil, and magnetically coupled to the first coil; wherein the first and second coils are magnetically coupled to each other such that the first and second coils strengthen a magnetic flux with each other.