Abstract:
In a laminated coil component, first coil conductor patterns define a coil opening that generates a magnetic flux in a first direction, second coil conductor patterns define a first coil opening that generates a magnetic flux in the first direction, and a second coil opening that generates a magnetic flux in a second direction. A difference in area between the first coil opening and the second coil opening determines a degree of coupling of the coil defined by the first coil conductor pattern and the coil defined by the second coil conductor pattern. This provides a close proximal arrangement of a plurality of coils proximally while significantly reducing or preventing unnecessary coupling between the coils.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a laminated coil component including a plurality of insulating layers that are laminated on each other, the insulating layers each including a conductor pattern, and a matching circuit provided with such a laminated coil component. 
         [0003]    2. Description of the Related Art 
         [0004]    Recently, with the miniaturization and high integration of electronic devices, a plurality of components to be built in or embedded have been required to be mounted in a proximity state in which the components are arranged closer to each other. However, with the mounting in the proximity state, the deterioration of the characteristics due to unnecessary coupling between adjacent components becomes a problem. 
         [0005]    In a case in which a plurality of coils (inductors) have to be proximally arranged, some measures such that the open surfaces of the coils are arranged not to face each other are required. Moreover, even in a case in which the open surfaces of the coils are located proximally (in a case of a structure in which the winding axes of the plurality of coils are stacked in the same direction), in order to reduce the unnecessary coupling between the inductors, Japanese Unexamined Patent Application Publication No. 11-016738, for example, has proposed a structure in which a ground conductor layer is inserted between the layers of each coil conductor pattern. 
         [0006]    As disclosed in Japanese Unexamined Patent Application Publication No. 11-016738, in the structure in which a ground conductor layer is inserted between the layers of each coil conductor pattern, the coils and the conductor layers are likely to be unnecessarily coupled to each other and the unnecessary coupling deteriorates the Q value of the coils. Therefore, the coil conductor pattern and the ground conductor layer still require a large space between the coil conductor pattern and the ground conductor layer. 
       SUMMARY OF THE INVENTION 
       [0007]    In view of the above, preferred embodiments of the present invention provide a laminated coil component capable of significantly reducing or preventing the unnecessary coupling between a plurality of coils while the coils are proximally arranged, and also a matching circuit provided with such a laminated coil component. 
         [0008]    A laminated coil component according to a preferred embodiment of the present invention includes a conductor pattern including a first coil conductor pattern and a second coil conductor pattern, at least one insulating layer on which the conductor pattern is provided, and at least one coil defined by the conductor patterns of the insulating layers that are laminated on each other, and the first coil conductor pattern defines a coil opening that generates a magnetic flux in a first direction; the second coil conductor pattern defines a first coil opening that generates a magnetic flux in the first direction and a second coil opening that generates a magnetic flux in a second direction opposite to the first direction; and the coil opening, in a plan view, overlaps a plurality of the coil openings including the first coil opening and the second coil opening. 
         [0009]    With the above configuration, even if a magnetic flux penetrates a coil defined by the first coil conductor pattern and a coil defined by the second coil conductor pattern, both of the coils are in an uncoupled state or in a relatively weak coupled state. Thus, the interlayer distance between the first coil conductor pattern and the second coil conductor pattern is reduced and a plurality of coils are arranged in a limited space. 
         [0010]    The outline of the first coil conductor pattern, in a plan view, may preferably overlap the outline of the second coil conductor pattern. This configuration enables both of the first coil conductor pattern and the second coil conductor pattern to define a coil of which the opening has a large diameter, in a limited space. In other words, in order to significantly reduce or prevent coupling, a coil having a small diameter does not need to be defined and thus the configuration makes it possible to configure a coil having necessary inductance with the small number of turns. 
         [0011]    In a preferred embodiment of the present invention, in a plan view, the total area of the first coil opening in which the coil opening of the first coil conductor pattern overlaps the first coil opening may be the same or substantially the same as the total area of the second coil opening in which the coil opening of the first coil conductor pattern overlaps the second coil opening. Accordingly, the coil defined by the first coil conductor pattern and the coil defined by the second coil conductor pattern are in a substantially uncoupled state. 
         [0012]    In another preferred embodiment of the present invention, in a plan view, the total area of the first coil opening in which the coil opening of the first coil conductor pattern overlaps the first coil opening may be different from the total area of the second coil opening in which the coil opening of the first coil conductor pattern overlaps the second coil opening. Accordingly, the coil defined by the first coil conductor pattern and the coil defined by the second coil conductor pattern are in a predetermined weakly coupled state. 
         [0013]    At least one of the first coil conductor pattern and the second coil conductor pattern may preferably be defined over a plurality of the insulating layers. This configuration provides a coil having a large inductance required for a limited occupied area. 
         [0014]    One of the first coil conductor pattern and the second coil conductor pattern may define a transformer configured by two coils coupled to each other, for example; and the other of the first coil conductor pattern and the second coil conductor pattern may define an inductor connected to the primary side or the secondary side of the transformer. This configuration provides a coil component including a filter including an inductor, for example; and a transformer impedance conversion circuit. 
         [0015]    One of the first coil conductor pattern and the second coil conductor pattern may define a plurality of coils coupled to each other; and the plurality of coils may be outer coil conductor patterns each provided in a position of holding the other of the first coil conductor pattern and the second coil conductor pattern between the plurality of coils in a laminated direction. This configuration, with outer coil conductor patterns, provides inductors that are weakly coupled to each other. 
         [0016]    A matching circuit according to a preferred embodiment of the present invention includes the laminated coil component described in the above, a band pass filter including two LC parallel resonant circuits in which the inductors are coupled to each other, and a transformer impedance conversion circuit configured by two inductors coupled to each other, and the inductors of the two LC parallel resonant circuits are defined by the outer coil conductor patterns; and the inductors of the transformer impedance conversion circuit are defined by the coil conductor patterns held between the outer coil conductor patterns. 
         [0017]    The above configuration provides a small matching circuit provided with a band pass filter and a transformer impedance conversion circuit. 
         [0018]    According to various preferred embodiments of the present invention, while the interlayer distance between the first coil conductor pattern and the second coil conductor pattern is small, the coil defined by the first coil conductor pattern and the coil defined by the second coil conductor pattern is able to be in an uncoupled state or in a relatively weakly coupled state. Thus, the interlayer distance between the first coil conductor pattern and the second coil conductor pattern is significantly reduced and a plurality of coils are arranged in a limited space. Moreover, even if the interlayer distance is small, the degree of coupling of the coil defined by the first coil conductor pattern and the coil defined by the second coil conductor pattern is able to be determined with high accuracy. 
         [0019]    The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is an exploded perspective view of a main portion of a laminated coil component  101  according to a first preferred embodiment of the present invention. 
           [0021]      FIG. 2  is a plan view showing respective insulating layers of the laminated coil component  101 . 
           [0022]      FIG. 3A  is a view showing first coil conductor patterns  11   a ,  11   b , and  11   c  that are overlapped, and  FIG. 3B  is a view showing second coil conductor patterns  12   a ,  12   b , and  12   c  that are overlapped. 
           [0023]      FIG. 4  is a cross sectional view showing the laminated coil component  101 . 
           [0024]      FIG. 5  is a circuit diagram of the laminated coil component  101 . 
           [0025]      FIG. 6  is an exploded perspective view of a main portion of a matching circuit  201  according to a second preferred embodiment of the present invention. 
           [0026]      FIG. 7  is a plan view showing respective insulating layers of the matching circuit  201 . 
           [0027]      FIG. 8  is a circuit diagram of the matching circuit  201 . 
           [0028]      FIG. 9  is an exploded perspective view of a main portion of a matching circuit  202  according to a third preferred embodiment of the present invention. 
           [0029]      FIG. 10  is a plan view showing respective insulating layers of the matching circuit  202 . 
           [0030]      FIG. 11A  is a view showing first coil conductor patterns  11   a ,  11   b , and  11   c  of the matching circuit  202  that are overlapped, and  FIG. 11B  is a view showing second coil conductor patterns  12   a ,  12   b , and  12   c  of the matching circuit  202  that are overlapped. 
           [0031]      FIG. 12  is a cross sectional view of a portion of layers including a coil conductor pattern of the matching circuit  202 . 
           [0032]      FIG. 13  is a circuit diagram of the matching circuit  202 . 
           [0033]      FIG. 14  is a plan view showing respective insulating layers of a matching circuit  203  according to a fourth preferred embodiment of the present invention. 
           [0034]      FIG. 15  is a circuit diagram of the matching circuit  203 . 
           [0035]      FIG. 16A ,  FIG. 16B , and  FIG. 16C  are plan views of a first coil conductor pattern and a second coil conductor pattern of a laminated coil component according to a fifth preferred embodiment of the present invention. 
           [0036]      FIG. 17A  and  FIG. 17B  are plan views of the first coil conductor pattern and the second coil conductor pattern of the laminated coil component according to the fifth preferred embodiment of the present invention. 
           [0037]      FIG. 18A  and  FIG. 18B  are plan views of the first coil conductor pattern and the second coil conductor pattern of the laminated coil component according to the fifth preferred embodiment of the present invention. 
           [0038]      FIG. 19  a plan view of the first coil conductor pattern and the second coil conductor pattern of the laminated coil component according to the fifth preferred embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0039]    Hereinafter, various preferred embodiments of the present invention will be described with reference to several specific examples. Each of the preferred embodiments is illustrative and other preferred embodiments can be further obtained by configurations shown in different preferred embodiments, the configuration being partially replaced and combined with each other. 
       First Preferred Embodiment 
       [0040]      FIG. 1  is an exploded perspective view of a main portion of a laminated coil component  101  according to a first preferred embodiment of the present invention. 
         [0041]    The laminated coil component  101  includes insulating layers  10   a  to  10   f  that are laminated on each other, each of the insulating layers  10   a  to  10   f  including at least one conductor pattern; and at least one coil defined by the conductor patterns. The conductor patterns include first coil conductor patterns  11   a ,  11   b , and  11   c , and second coil conductor patterns  12   a ,  12   b , and  12   c . In other words, the insulating layers  10   a ,  10   b , and  10   c  include the first coil conductor patterns  11   a ,  11   b , and  11   c , respectively, and the insulating layers  10   d ,  10   e , and  10   f  include the second coil conductor patterns  12   a ,  12   b , and  12   c , respectively. The respective conductor patterns are interlayer-connected to each other through via conductors (not shown) at predetermined positions. The laminated coil component includes an external terminal on an end surface or a bottom surface of a laminate, which is not shown in  FIG. 1 . 
         [0042]    The first end of the first coil conductor pattern  11   a  is connected to a terminal P 1 . The second end of the first coil conductor pattern  11   a  is connected to the first end of the first coil conductor pattern  11   b , and the second end of the first coil conductor pattern  11   b  is connected to the first end of the first coil conductor pattern  11   c . The second end of the first coil conductor pattern  11   c  is connected to a terminal P 2 . 
         [0043]    The first end of the second coil conductor pattern  12   a  is connected to a terminal P 4 . The second end of the second coil conductor pattern  12   a  is connected to the first end of the second coil conductor pattern  12   b , and the second end of the second coil conductor pattern  12   b  is connected to the first end of the second coil conductor pattern  12   c . The second end of the second coil conductor pattern  12   c  is connected to a terminal P 3 . 
         [0044]      FIG. 2  is a plan view showing the respective insulating layers of the laminated coil component  101 .  FIG. 2  shows an example of the direction of an electric current flowing in each of the coil conductor patterns and the direction of a magnetic flux passing through a coil opening.  FIG. 3A  is a view showing first coil conductor patterns  11   a ,  11   b , and  11   c  that are overlapped, and  FIG. 3B  is a view showing second coil conductor patterns  12   a ,  12   b , and  12   c  that are overlapped.  FIG. 4  is a cross sectional view showing the laminated coil component  101 . 
         [0045]    As shown by the arrows in  FIG. 2 , an electric current flows in each of the coil conductor patterns, which generates magnetic fluxes in directions as shown by a cross mark and a dot mark in  FIG. 2 . In this way, the direction of the electric current is shown by an arrow and the direction of a magnetic flux is shown by a cross mark and a dot mark, which is also applied to the other figures to be shown below. 
         [0046]    As shown in  FIG. 3A  and  FIG. 3B , the first coil conductor patterns  11   a ,  11   b , and  11   c  define a coil opening CA 1  that generates a magnetic flux in a first direction (depth direction of the paper surface, for example). The second coil conductor patterns  12   a ,  12   b , and  12   c  define a first coil opening CA 21  that generates a magnetic flux in the first direction (depth direction of the paper surface), and a second coil opening CA 22  that generates a magnetic flux in a second direction (front direction of the paper surface). The area of the first coil opening CA 21  is equal or substantially equal to the area of the second coil opening CA 22 . 
         [0047]    The coil opening CA 1  of the first coil conductor patterns  11   a ,  11   b , and  11   c , in a plan view, overlap the first coil opening CA 21  and the second coil opening CA 22  of the second coil conductor patterns  12   a ,  12   b , and  12   c.    
         [0048]    As shown in  FIG. 4 , the first coil conductor patterns  11   a ,  11   b , and  11   c  generate a magnetic flux φ 1  in the first direction and the second coil conductor patterns  12   a ,  12   b , and  12   c  generate a magnetic flux φ 21  in the first direction and a magnetic flux φ 22  in the second direction, respectively. 
         [0049]    By the above configuration, the magnetic flux φ 22  passing through the coil opening CA 22  defined by the second coil conductor patterns  12   a ,  12   b , and  12   c  acts in a direction in which the magnetic flux φ 22  and the magnetic flux φ 1  passing through the coil opening CA 1  defined by the first coil conductor patterns  11   a ,  11   b , and  11   c  strengthen each other (the inductance is increased); and the magnetic flux φ 21  passing through the coil opening CA 21  acts in a direction in which the magnetic flux φ 21  and the magnetic flux φ 1  passing through the coil opening CA 1  weaken each other (the inductance is decreased). 
         [0050]      FIG. 5  is a circuit diagram of the laminated coil component  101 . A first inductor L 1  is connected between terminals P 1  and P 2 , and a second inductor L 2  is connected between terminals P 3  and P 4 . The second inductor L 2  is defined by inductors L 21  and L 22  that are connected in series to each other. In the present preferred embodiment of the present invention, the inductor L 1  is an inductor defined by the first coil conductor patterns  11   a ,  11   b , and  11   c ; and the inductor L 2  is an inductor defined by the second coil conductor patterns  12   a ,  12   b , and  12   c . The inductors L 21  and L 22  are defined, respectively, by a portion in which the second coil conductor patterns  12   a ,  12   b , and  12   c  define the coil openings CA 21  and CA 22 . In this way, the inductor L 1  and the inductor L 22  are coupled with the same polarity and the inductor L 1  and the inductor L 21  are coupled with the reverse polarity. 
         [0051]    In other words, even when the coil opening CA 1  defined by the first coil conductor patterns  11   a ,  11   b , and  11   c  and the coil openings CA 21  and CA 22  defined by the second coil conductor patterns  12   a ,  12   b , and  12   c  are passed through by a magnetic flux, both of the coils are equivalently uncoupled to each other. Therefore, even when the interlayer distance between the first coil conductor patterns  11   a ,  11   b , and  11   c  and the second coil conductor patterns  12   a ,  12   b , and  12   c  is reduced, the unnecessary coupling does not occur, so that two coils are able to be arranged in a limited space. 
       Second Preferred Embodiment 
       [0052]      FIG. 6  is an exploded perspective view of a main portion of a matching circuit  201  according to a second preferred embodiment of the present invention.  FIG. 7  is a plan view showing the respective insulating layers of the matching circuit  201 . 
         [0053]    The matching circuit  201  includes insulating layers  10   a  to  101  that are laminated on each other, each of the insulating layers  10   a  to  101  including at least one conductor pattern; and at least one coil defined by the conductor patterns. The conductor patterns include first coil conductor patterns  11   a  to  11   d , and second coil conductor patterns  12   a  to  12   c . The respective conductor patterns are interlayer-connected to each other through via conductors (not shown) at predetermined positions. The insulating layers  10   a  to  10   d  include first coil conductor patterns  11   a  to  11   d . The insulating layers  10   e  to  10   g  include second coil conductor patterns  12   a  to  12   c . The insulating layers  10   h  to  10   j  include capacitor electrodes  21  to  23 . The insulating layer  10   k  includes a ground electrode  24 . The lowermost insulating layer  101  includes input/output terminals  31  and  32  and ground terminals  33  and  34 . 
         [0054]      FIG. 8  is a circuit diagram of the matching circuit  201 . The coil conductor patterns  11   b  and  11   c  define an inductor L 1 , and the coil conductor patterns  11   a  and  11   d  define an inductor L 2 . The coil conductor patterns  12   a ,  12   b , and  12   c  define an inductor L 3 . The capacitor electrode  23  and the ground electrode  24  define a capacitor C 1 , and the capacitor electrodes  21 ,  22 , and  23  define a capacitor C 2 . 
         [0055]    In  FIG. 8 , the inductor L 1  and the inductor L 2  define an impedance conversion circuit having an auto transformer (single winding transformer) structure. The inductors L 1  and L 2  are coupled to each other through a mutual inductance M. In the present preferred embodiment of the present invention, the inductance of the inductors L 1  and L 2  is indicated by L 1  and L 2  and the mutual inductance is indicated by M, the impedance conversion circuit is transformed into a T-type equivalent circuit configured by the inductors of (L 1 +M), (L 2 +M), and (−M) from the left in order. Accordingly, the impedance conversion ratio of the transformer is {(L 1 +M)+(L 2 +M)}:{(L 2 +M)+(−M)}=(L 1 +L 2 +2M):L 2 . 
         [0056]    In  FIG. 8 , the capacitors C 1  and C 2  and the inductor L 3  define and function as a band elimination filter that significantly reduces or prevents an unnecessary frequency band. Since the inductor L 3  of the filter and the inductors L 1  and L 2  of the above described transformer for impedance conversion are not coupled substantially, the filter and the transformer act independently without interfering with each other. 
       Third Preferred Embodiment 
       [0057]      FIG. 9  is an exploded perspective view of a main portion of a matching circuit  202  according to a third preferred embodiment of the present invention.  FIG. 10  is a plan view showing the respective insulating layers of the matching circuit  202 .  FIG. 11A  is a view showing first coil conductor patterns  11   a ,  11   b ,  11   c , and  11   d  of the matching circuit  202  that are overlapped, and  FIG. 11B  is a view showing second coil conductor patterns  12   a ,  12   b , and  12   c  of the matching circuit  202  that are overlapped.  FIG. 12  is a cross sectional view of a portion of layers including a coil conductor pattern of the matching circuit  202 . Furthermore,  FIG. 13  is a circuit diagram of the matching circuit  202 . 
         [0058]    The matching circuit  202  differs from the matching circuit  201  according to the second preferred embodiment of the present invention in that the second coil conductor patterns  12   a ,  12   b , and  12   c  have different shapes. As shown in  FIG. 9  and  FIG. 10 , the second coil conductor patterns  12   a ,  12   b , and  12   c  are point asymmetric to each other. As shown in  FIG. 11 , the first coil conductor patterns  11   a ,  11   b ,  11   c , and  11   d  define a coil opening CA 1  that generates a magnetic flux in a first direction (depth direction of the paper surface, for example). The second coil conductor patterns  12   a ,  12   b , and  12   c  define a first coil opening CA 21  that generates a magnetic flux in the first direction (depth direction of the paper surface), and a second coil opening CA 22  that generates a magnetic flux in a second direction (front direction of the paper surface). Since the second coil conductor patterns  12   a ,  12   b , and  12   c  are point asymmetric to each other, the area of the first coil opening CA 21  is different from the area of the second coil opening CA 22 . The coil opening CA 1  of the first coil conductor patterns  11   a ,  11   b ,  11   c , and  11   d  in a plan view, overlap the first coil opening CA 21  and the second coil opening CA 22  of the second coil conductor patterns  12   a ,  12   b , and  12   c.    
         [0059]    As shown in  FIG. 12 , the first coil conductor patterns  11   a ,  11   b ,  11   c , and  11   d  generate a magnetic flux φ 1  in the first direction and the second coil conductor patterns  12   a ,  12   b , and  12   c  generate a magnetic flux φ 21  in the first direction and a magnetic flux φ 22  in the second direction, respectively. By the above configuration, the magnetic flux φ 22  passing through the coil opening CA 22  defined by the second coil conductor patterns  12   a ,  12   b , and  12   c  acts in a direction in which the magnetic flux φ 22  and the magnetic flux φ 1  passing through the coil opening CA 1  defined by the first coil conductor patterns  11   a ,  11   b ,  11   c , and  11   d  strengthen each other (the inductance is increased); and the magnetic flux φ 21  passing through the coil opening CA 21  acts in a direction in which the magnetic flux φ 21  and the magnetic flux φ 1  passing through the coil opening CA 1  weaken each other (the inductance is decreased). In the present preferred embodiment of the present invention, since the coil opening CA 21  through which the magnetic flux φ 21  passes is larger than the coil opening CA 22  through which the magnetic flux φ 22  passes, the coils (L 1  and L 2 ) defined by the first coil conductor patterns  11   a ,  11   b ,  11   c , and  11   d  are coupled to the coil (L 3 ) defined by the second coil conductor patterns  12   a ,  12   b , and  12   c  by a difference in intensity of the magnetic fluxes φ 21  and φ 22 . More accurately, mainly, with the ratio of a difference in area of the coil openings CA 21  and CA 22  and the area of the coil opening CA 1 , the coupling coefficient of the coil (L 1  and L 2 ) defined by the first coil conductor patterns  11   a ,  11   b ,  11   c , and  11   d  and the coil (L 3 ) defined by the second coil conductor patterns  12   a ,  12   b , and  12   c  is determined. 
         [0060]    In the matching circuit  202  shown in  FIG. 13 , the impedance conversion is performed by the transformer ratio of the transformer defined by the inductors L 1  and L 2 . In addition, the band elimination filter including the inductor L 3  eliminates a secondary or tertiary harmonic component of a use frequency band. However, compared with a case of a single transformer by connecting the inductor L 3  to the inductor L 1  of the transformer by the inductors L 1  and L 2  in series, a deviation in the transformer ratio of the transformer is generated. According to the third preferred embodiment of the present invention, the inductor L 3  is weakly coupled to the inductors (L 1  and L 2 ), which corrects the transformer ratio of the transformer by the inductors L 1  and L 2 . 
         [0061]    Accordingly, even when the interlayer distance of the first coil conductor patterns  11   a  to  11   d  and the second coil conductor patterns  12   a  to  12   c  is reduced, desired weak coupling occurs, so that a matching circuit including a plurality of coils is able to be provided in a limited space. In addition, even when the interlayer distance is small, the degree of coupling between the inductor L 3  and the inductors (L 1  and L 2 ) is able to be determined with high accuracy. 
       Fourth Preferred Embodiment 
       [0062]      FIG. 14  is a plan view showing the respective insulating layers of a matching circuit  203  according to a fourth preferred embodiment of the present invention. In the matching circuit  203 , the insulating layers  10   d ,  10   e , and  10   f  include the first coil conductor patterns  11   a ,  11   b , and  11   c , and the insulating layers  10   c  and  10   g  include the second coil conductor patterns  12  and  13 . In addition, the insulating layers  10   a  and  10   b  include the capacitor electrodes  21  and  22 , and the insulating layers  10   h  and  10   i  include the capacitor electrode  23  and the ground electrode  24 , respectively. 
         [0063]    The first end of the first coil conductor pattern  11   a  is connected to the capacitor electrode  22 , and the second end of the first coil conductor pattern  11   a  is connected to the first end of the first coil conductor pattern  11   b . The second end of the first coil conductor pattern  11   b  is connected to the first end of the first coil conductor pattern  11   c . The second end of the first coil conductor pattern  11   c  is connected to the ground electrode  24 . The first end of the second coil conductor pattern  12  is connected to the capacitor electrode  22 , and the first end of the second coil conductor pattern  13  is connected to the capacitor electrode  23 . Moreover, the first ends of the second coil conductor patterns  12  and  13  are connected to the ground electrode  24 , respectively. 
         [0064]      FIG. 15  is a circuit diagram of the matching circuit  203 . The coil conductor patterns  11   a  and  11   b  define an inductor L 1 , and the coil conductor patterns  11   b  and  11   c  define an inductor L 2 . The coil conductor pattern  12  defines an inductor L 3 , and the coil conductor pattern  13  defines an inductor L 4 . The capacitor electrodes  21  and  22  define a capacitor C 1 , and the capacitor electrode  23  and the ground electrode  24  define a capacitor C 2 . 
         [0065]    In  FIG. 15 , the inductor L 1  and the inductor L 2  define an impedance conversion circuit having an auto transformer (single winding transformer) structure. The parallel resonant circuit defined by the capacitor C 2  and the inductor L 4  and the parallel resonant circuit defined by the capacitor C 1  and the inductor L 3  are coupled to each other by transformer coupling of the inductor L 3  and the inductor L 4 . The capacitors C 1  and C 2  and the inductors L 3  and L 4  define a band pass filter. 
         [0066]    The first coil conductor patterns  11   a ,  11   b , and  11   c  define a coil opening that generates a magnetic flux in a first direction, and the second coil conductor patterns  12  and  13  define a first coil opening that generates a magnetic flux in the first direction and a second coil opening that generates a magnetic flux in a second direction. Then, the coil opening of the first coil conductor pattern, in a plan view, overlaps a plurality of the coil openings including the first coil opening and the second coil opening of the second coil conductor pattern. These relationships preferably are the same or substantially the same as the relationships shown in the first to third preferred embodiments of the present invention. Thus, the inductors (L 3  and L 4 ) of the filter and the inductors (L 1  and L 2 ) of the transformer for impedance conversion are not coupled substantially and the filter and the transformer act independently without interfering with each other. 
         [0067]    According to this fourth preferred embodiment of the present invention, the second coil conductor patterns  12  and  13  are not connected and are separated from each other in terms of direct current. In addition, the second coil conductor patterns  12  and  13  are arranged so as to hold the first coil conductor pattern between the second coil conductor patterns  12  and  13  in a laminated direction. 
         [0068]    According to this configuration, in spite of the fact that the first coil conductor and the second coil conductor are adjacent to each other in the laminated direction, the inductors (L 1  and L 2 ) defined by the first coil conductor and the inductors (L 3  and L 4 ) defined by the second coil conductor are hardly coupled at all and furthermore the inductors L 3  and L 4  defined by the second coil conductor patterns  12  and  13  of which the layers are separated are coupled to each other. 
         [0069]    In addition, since the layer interval between the second coil conductor patterns  12  and  13  is comparatively large, the coupling coefficient between the inductors L 3  and L 4  is able to be made smaller. Accordingly, the pass band width of the band pass filter is able to be set to a desired small band. 
       Fifth Preferred Embodiment 
       [0070]    In a fifth preferred embodiment of the present invention, several examples of the first coil conductor pattern and the second coil conductor pattern are shown with reference to  FIG. 16A ,  FIG. 16B ,  FIG. 16C ,  FIG. 17A ,  FIG. 17B ,  FIG. 18A ,  FIG. 18B , and  FIG. 19 . In any of the examples, the first coil conductor pattern  11  defines a coil opening that generates a magnetic flux in a first direction, and the second coil conductor pattern  12  defines a first coil opening that generates a magnetic flux in the first direction and a second coil opening that generates a magnetic flux in a second direction. 
         [0071]    In the example of  FIG. 16A , the second coil conductor pattern  12  defines a first coil opening that generates a magnetic flux in the first direction, and two second coil openings that generate magnetic fluxes in the second direction. In the example of  FIG. 16B , the second coil conductor pattern  12  defines two first coil openings that generate magnetic fluxes in the first direction, and two second coil openings that generate magnetic fluxes in the second direction. In the example of  FIG. 16C , the second coil conductor pattern  12  defines two first coil openings that generate magnetic fluxes in the first direction, and three second coil openings that generate magnetic fluxes in the second direction. As shown in the examples, the second coil conductor pattern may be provided so as to define three or more coil openings. 
         [0072]    In the examples of  FIG. 17A  and  FIG. 17B , the second coil conductor pattern  12  defines a first coil opening that generates a magnetic flux in the first direction, and the two second coil openings that generate magnetic fluxes in a second direction. The shape of the coil opening defined by the second coil conductor pattern is not limited to a triangle or a trapezoidal shape and, as shown in the example of  FIG. 17A , the two coil openings defined by the second coil conductor pattern may have a rectangular double spiral shape. Alternatively, as shown in the example of  FIG. 17B , the ends as a starting point and an ending point may be in positions near the center of the region in which the patterns are provided. 
         [0073]    In the examples of  FIG. 18A  and  FIG. 18B , the second coil conductor pattern  12  defines a first coil opening that generates a magnetic flux in the first direction, and the second coil openings that generate magnetic fluxes in the second direction. In this example, the first coil opening and the second coil openings are arranged in a matrix in a plane. 
         [0074]    In the example of  FIG. 19 , two second coil conductor patterns  12 A and  12 B are provided. The second coil conductor patterns  12 A and  12 B define a first coil opening that generates a magnetic flux in the first direction, and two second coil openings that generate magnetic fluxes in the second direction. Therefore, the second coil conductor pattern  12 A and the first coil conductor pattern  11  are not substantially coupled to each other and the second coil conductor pattern  12 B and the first coil conductor pattern  11  are not substantially coupled to each other. 
       Other Preferred Embodiments 
       [0075]    While the foregoing preferred embodiments show examples in which, in a plan view, the coil opening of the first coil conductor pattern preferably entirely overlaps the first coil opening and the second coil opening of the second coil conductor pattern, the coil opening of the first coil conductor pattern, in a plan view, may not entirely overlap the first coil opening and the second coil opening of the second coil conductor pattern and may overlap a plurality of coil openings including the first coil opening and the second coil opening of the second coil conductor pattern. 
         [0076]    In addition, the first coil conductor pattern may not be limited to a pattern defining a single coil opening and may define a plurality of coil openings. In such a case, all coil openings or one coil opening of the first coil conductor pattern may entirely overlap the first coil opening and the second coil opening of the second coil conductor pattern. 
         [0077]    Finally, the above described preferred embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the following claims, not by the foregoing preferred embodiments. Further, the scope of the present invention is intended to include the scopes of the claims and all possible changes and modifications within the senses and scopes of equivalents. 
         [0078]    While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.