Wireless ic device

Abstract

An electromagnetic coupling module includes a wireless IC chip and a functional substrate. The electromagnetic coupling module is mounted on a radiation plate, preferably using an adhesive, for example. On the upper surface of a base material of the radiation plate, two long radiation electrodes are provided. On the undersurface of the functional substrate, capacitive coupling electrodes that individually face inner ends of the radiation electrodes are provided. A matching circuit arranged to perform the impedance matching between the wireless IC chip and each of the radiation electrodes includes the capacitive coupling electrodes. As a result, it is possible to reduce the size, facilitate the design, and reduce the cost of a wireless IC device.

1 . A wireless IC device comprising:
 a wireless IC chip;   a radiation plate including a radiation electrode; and   a functional substrate including a matching circuit arranged to perform impedance matching between the wireless IC chip and the radiation electrode, the functional substrate including a coupling electrode coupled to the radiation electrode, inductance elements, and a capacitance element; wherein   the matching circuit included in the functional substrate has a configuration such that a relationship between a reactance component of an impedance obtained by viewing the wireless IC chip from a connecting portion connecting the wireless IC chip and the functional substrate to each other and a reactance component of an impedance obtained by viewing the radiation electrode from the connecting portion connecting the wireless IC chip and the functional substrate to each other is a conjugate relationship.   
     
     
         2 . The wireless IC device according to  claim 1 , wherein the coupling electrode is electromagnetically coupled to the radiation electrode. 
     
     
         3 . The wireless IC device according to  claim 1 , wherein the functional substrate includes a multilayer substrate including laminated dielectric layers on which electrode patterns are provided. 
     
     
         4 . The wireless IC device according to  claim 1 , wherein
 the radiation electrode has an elongated configuration;   the coupling electrode includes first and second external coupling electrodes that individually occupy two areas divided from the functional substrate; and   one end of the radiation electrode is coupled to the first external coupling electrode and another end of the radiation electrode is coupled to the second external coupling electrode.   
     
     
         5 . The wireless IC device according to  claim 4 , wherein
 the radiation electrode is a loop-shaped radiation electrode arranged such that both ends of the radiation electrode face each other;   a first one of the both ends of the radiation electrode is coupled to the first external coupling electrode; and   a second one of the both ends of the radiation electrode is coupled to the second external coupling electrode.   
     
     
         6 . The wireless IC device according to  claim 4 , further comprising an auxiliary matching circuit portion including a matching electrode arranged to connect a location near the first one of the both ends of the radiation electrode to a location near the second one of the both ends of the radiation electrode, a portion of the radiation electrode extending from the first one of the both ends of the radiation electrode to a location near the one of the both ends of the radiation electrode, and a portion of the radiation electrode extending from the second of the both ends of the radiation electrode to a location near the second of the both ends of the radiation electrode. 
     
     
         7 . The wireless IC device according to  claim 1 , wherein
 the inductance elements are loop-shaped inductance elements; and   winding axes of the loop-shaped inductance elements are arranged so that they cross an area in which the radiation electrode is located.   
     
     
         8 . The wireless IC device according to  claim 1 , wherein the coupling electrode is a capacitive coupling electrode that faces the radiation electrode and is capacitively coupled to the radiation electrode. 
     
     
         9 . The wireless IC device according to  claim 8 , wherein
 the capacitive coupling electrode is provided on a surface of the functional substrate facing the radiation plate;   the radiation electrode is provided on a surface of the radiation plate facing the functional substrate; and   the functional substrate is attached to the radiation plate so that the capacitive coupling electrode and the radiation electrode face each other.   
     
     
         10 . The wireless IC device according to  claim 8 , wherein the external coupling electrode included in the functional substrate extends to a surface other than the surface of the functional substrate facing the radiation plate. 
     
     
         11 . The wireless IC device according to  claim 1 , wherein
 the coupling electrode is a loop-shaped external coupling electrode; and   the loop-shaped external coupling electrode is magnetically coupled to the radiation electrode.   
     
     
         12 . The wireless IC device according to  claim 11 , wherein
 at least one of the inductance elements has a double helix shape in which two different linear electrodes are adjacent to each other; and   one end of one of the two different linear electrodes is electrically connected to one end of the other one of the two different linear electrodes.   
     
     
         13 . The wireless IC device according to  claim 11 , wherein
 the radiation electrode is a loop-shaped radiation electrode; and   the loop-shaped radiation electrode is electromagnetically coupled to the inductance elements included in the functional substrate.   
     
     
         14 . The wireless IC device according to  claim 1 , wherein the matching circuit includes an element included in the functional substrate and an element mounted on the functional substrate. 
     
     
         15 . The wireless IC device according to  claim 1 , further comprising a protection film covering at least one of the wireless IC chip, the functional substrate, and the radiation plate.