U.S. patent application number 12/235753 was filed with the patent office on 2009-01-22 for radio frequency ic device and electronic apparatus.
This patent application is currently assigned to MURATA MANUFACTURING CO., LTD.. Invention is credited to Yuya DOKAI, Nobuo IKEMOTO, Satoshi ISHINO, Takeshi KATAYA, Noboru KATO, Ikuhei KIMURA.
Application Number | 20090021352 12/235753 |
Document ID | / |
Family ID | 46332014 |
Filed Date | 2009-01-22 |
United States Patent
Application |
20090021352 |
Kind Code |
A1 |
KATAYA; Takeshi ; et
al. |
January 22, 2009 |
RADIO FREQUENCY IC DEVICE AND ELECTRONIC APPARATUS
Abstract
A radio frequency IC device includes a radio frequency IC chip
arranged to process a transmitted/received signal, a printed
circuit board on which the radio frequency IC chip is mounted, an
electrode arrange on the circuit board, and a loop electrode that
is arranged on the circuit board so that the loop electrode is
electrically connected to the radio frequency IC chip and is
coupled to the electrode by electromagnetic coupling. The electrode
is coupled to the radio frequency IC chip via the loop electrode so
as to transmit or receive a high-frequency signal. A power supply
circuit board including a resonance circuit and/or a matching
circuit may be disposed between the radio frequency IC chip and the
loop electrode.
Inventors: |
KATAYA; Takeshi; (Ritto-shi,
JP) ; KATO; Noboru; (Moriyama-shi, JP) ;
ISHINO; Satoshi; (Kusatsu-shi, JP) ; IKEMOTO;
Nobuo; (Moriyama-shi, JP) ; KIMURA; Ikuhei;
(Nara-shi, JP) ; DOKAI; Yuya; (Nagaokakyo-shi,
JP) |
Correspondence
Address: |
MURATA MANUFACTURING COMPANY, LTD.;C/O KEATING & BENNETT, LLP
1800 Alexander Bell Drive, SUITE 200
Reston
VA
20191
US
|
Assignee: |
MURATA MANUFACTURING CO.,
LTD.
Nagaokakyo-shi
JP
|
Family ID: |
46332014 |
Appl. No.: |
12/235753 |
Filed: |
September 23, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11851661 |
Sep 7, 2007 |
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12235753 |
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PCT/JP2008/052129 |
Feb 8, 2008 |
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11851661 |
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PCT/JP2008/055962 |
Mar 27, 2008 |
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PCT/JP2008/052129 |
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Current U.S.
Class: |
340/10.1 |
Current CPC
Class: |
H04Q 2213/13095
20130101; H05K 1/0243 20130101; H05K 1/141 20130101; H01Q 1/2225
20130101; H05K 1/16 20130101; G06K 19/0775 20130101; H01Q 7/00
20130101; H05K 1/0239 20130101; G06K 19/07749 20130101; H05K
2201/10098 20130101; H01L 2224/16225 20130101; H01L 2224/16227
20130101; H01Q 1/38 20130101; H01Q 1/48 20130101 |
Class at
Publication: |
340/10.1 |
International
Class: |
H04Q 5/22 20060101
H04Q005/22 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 18, 2007 |
JP |
2007-186392 |
Claims
1. A radio frequency IC device comprising: a radio frequency IC
chip arranged to process a transmitted/received signal; a circuit
board on which the radio frequency IC chip is mounted; an electrode
arranged on the circuit board; and a loop electrode arranged on the
circuit board so that the loop electrode is coupled to the radio
frequency IC chip and to the electrode.
2. The radio frequency IC device according to claim 1, wherein the
loop electrode and the electrode arranged on the circuit board are
arranged on the same main surface of the circuit board.
3. The radio frequency IC device according to claim 1, wherein at
least one of the loop electrode and the electrode arranged on the
circuit board is disposed in the circuit board.
4. The radio frequency IC device according to claim 1, wherein the
loop electrode and the electrode arranged on the circuit board are
electrically isolated from each other.
5. The radio frequency IC device according to claim 1, wherein the
loop electrode and the electrode arranged on the circuit board are
electrically connected to each other.
6. The radio frequency IC device according to claim 1, wherein the
circuit board is a multilayer board in which one of a plurality of
dielectric layers and a plurality of magnetic layers are
laminated.
7. The radio frequency IC device according to claim 1, wherein the
loop electrode provides an impedance matching function.
8. The radio frequency IC device according to claim 6, wherein the
loop electrode is provided on a main surface of the circuit board
and is provided on at least one of the plurality of dielectric
layers or on at least one of the plurality of magnetic layers.
9. The radio frequency IC device according to claim 6, wherein the
loop electrode is provided on a plurality of layers, and the loop
electrode provided on at least one of the plurality of layers is
different from the loop electrodes provided on the other ones of
the plurality of layers in loop size.
10. The radio frequency IC device according to claim 9, wherein end
portions of the loop electrode that is different from the loop
electrodes in loop size are coupled to one of the radio frequency
IC chip and the electromagnetic coupling module.
11. The radio frequency IC device according to claim 1, wherein a
matching electrode is disposed on an inner side of the loop
electrode.
12. An electronic apparatus comprising the radio frequency IC
device according to claim 1.
13. A radio frequency IC device comprising: an electromagnetic
coupling module including a radio frequency IC arranged to process
a transmitted/received signal and a power supply circuit board
including an inductance element coupled to the radio frequency IC;
a circuit board on which the electromagnetic coupling module is
mounted; an electrode arranged on the circuit board; and a loop
electrode arranged on the circuit board so that the loop electrode
is coupled to the power supply circuit board and to the
electrode.
14. The radio frequency IC device according to claim 13, wherein a
resonance circuit is provided in the power supply circuit
board.
15. The radio frequency IC device according to claim 13, wherein a
matching circuit is provided in the power supply circuit board.
16. The radio frequency IC device according to claim 13, wherein
the loop electrode and the electrode arranged on the circuit board
are arranged on the same main surface of the circuit board.
17. The radio frequency IC device according to claim 13, wherein at
least one of the loop electrode and the electrode arranged on the
circuit board is disposed in the circuit board.
18. The radio frequency IC device according to claim 13, wherein
the loop electrode and the electrode arranged on the circuit board
are electrically isolated from each other.
19. The radio frequency IC device according to claim 13, wherein
the loop electrode and the electrode arranged on the circuit board
are electrically connected to each other.
20. The radio frequency IC device according to claim 13, wherein
the circuit board is a multilayer board in which one of a plurality
of dielectric layers and a plurality of magnetic layers are
laminated.
21. The radio frequency IC device according to claim 13, wherein
the loop electrode provides an impedance matching function.
22. The radio frequency IC device according to claim 20, wherein
the loop electrode is provided on a main surface of the circuit
board and is provided on at least one of the plurality of
dielectric layers or on at least one of the plurality of magnetic
layers.
23. The radio frequency IC device according to claim 20, wherein
the loop electrode is provided on a plurality of layers, and the
loop electrode provided on at least one of the plurality of layers
is different from the loop electrodes provided on the other ones of
the plurality of layers in loop size.
24. The radio frequency IC device according to claim 23, wherein
end portions of the loop electrode that is different from the loop
electrodes in loop size are coupled to one of the radio frequency
IC chip and the electromagnetic coupling module.
25. The radio frequency IC device according to claim 13, wherein a
matching electrode is disposed on an inner side of the loop
electrode.
26. The radio frequency IC device according to claim 13, wherein an
outer electrode is provided on a surface of the power supply
circuit board, the outer electrode being coupled to at least one of
a resonance circuit and a matching circuit by electromagnetic field
coupling and being electrically connected to the loop
electrode.
27. The radio frequency IC device according to claim 13, wherein
the power supply circuit board includes a multilayer board.
28. The radio frequency IC device according to claim 13, wherein
the power supply circuit board includes a flexible board.
29. An electronic apparatus comprising the radio frequency IC
device according to claim 1.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to radio frequency IC devices,
and, more particularly, to a radio frequency IC device including a
radio frequency IC chip used in an RFID (Radio Frequency
Identification) system and an electronic apparatus including the
radio frequency IC device.
[0003] 2. Description of the Related Art
[0004] Recently, an RFID system has been developed as a product
management system in which a reader/writer arranged to generate an
induction field communicates with an IC chip (hereinafter also
referred to as an IC tag or a radio frequency IC chip) attached to
a product or a case in a non-contact manner so as to obtain
predetermined information stored in the IC chip.
[0005] Japanese Unexamined Patent Application Publication
(Translation of PCT Application) No. 11-515094 discloses an RFID
tag including an IC chip mounted on the main surface of a printed
circuit board and an antenna provided in the printed circuit board.
In this RFID tag, the antenna and the IC chip are electrically
connected to each other. The miniaturization of the RFID tag is
achieved by providing the antenna in the printed circuit board.
[0006] However, the number of manufacturing processes required to
produce the RFID tag is increased in order to prepare the dedicated
antenna, and a space is required for the dedicated antenna. This
leads to increases in the manufacturing cost and size of the RFID
tag. As illustrated in FIG. 2 in Japanese Unexamined Patent
Application Publication (Translation of PCT Application) No.
11-515094, the number of manufacturing processes is increased
especially if an antenna having a meander shape is formed, since
internal electrodes included in a plurality of layers must be
processed. Furthermore, in order to achieve the impedance matching
between the IC chip and the antenna, a matching section is
required. If the matching section is disposed between the antenna
and the IC chip, the size of the antenna is increased. Furthermore,
if the IC chip is modified, the shape of the antenna must be
changed.
SUMMARY OF THE INVENTION
[0007] To overcome the problems described above, preferred
embodiments of the present invention provide a small radio
frequency IC device capable of easily achieving impedance matching
without using a dedicated antenna and an electronic apparatus
including the radio frequency IC device.
[0008] A radio frequency IC device according to a first preferred
embodiment of the present invention includes a radio frequency IC
chip arranged to process a transmitted/received signal, a circuit
board on which the radio frequency IC chip is mounted, an electrode
arranged on the circuit board, and a loop electrode that is
arranged on the circuit board so that the loop electrode is coupled
to the radio frequency IC chip and the electrode.
[0009] A radio frequency IC device according to a second preferred
embodiment of the present invention includes an electromagnetic
coupling module including a radio frequency IC chip arranged to
process a transmitted/received signal and a power supply circuit
board that includes an inductance element coupled to the radio
frequency IC chip, a circuit board on which the electromagnetic
coupling module is mounted, an electrode arranged on the circuit
board, and a loop electrode that is arranged on the circuit board
so that the loop electrode is coupled to the power supply circuit
board and the electrode.
[0010] In the radio frequency IC device according to the first
preferred embodiment, a radio frequency IC chip or a power supply
circuit board is preferably coupled to an electrode arranged at a
circuit board, for example, a ground electrode via a loop
electrode. The electrode arranged on the circuit board functions as
a radiation plate (an antenna) for the radio frequency IC chip.
That is, the electrode receives a signal, and the radio frequency
IC chip receives the signal from the electrode via the loop
electrode and is operated by the received signal. A response signal
output from the radio frequency IC chip is transmitted to the
electrode via the loop electrode, and is then emitted from the
electrode to the outside. Accordingly, a dedicated antenna is not
required, and a space is not required for the dedicated antenna.
The loop electrode can perform the impedance matching between the
radio frequency IC chip and the electrode. Accordingly, a matching
section is not necessarily required. Therefore, the efficiency of
signal transmission between the radio frequency IC chip and the
electrode is improved.
[0011] In a radio frequency IC device according to the second
preferred embodiment, a power supply circuit board is disposed
between a radio frequency IC, for example, a radio frequency IC
chip and a loop electrode. This power supply circuit board includes
a resonance circuit including an inductance element and/or a
matching circuit. A frequency to be used is set by the resonance
circuit and/or the matching circuit. If the radio frequency IC chip
is changed in accordance with a frequency used by an RFID system,
only a change in design of the resonance circuit and/or the
matching circuit is required. It is not necessary to change the
shape, size, and/or location of a radiation plate (electrode) or
the state of coupling between the loop electrode and the electrode
or the power supply circuit board. The resonance circuit and/or the
matching circuit can also function to achieve the impedance
matching between the radio frequency IC chip and the electrode.
Accordingly, the efficiency of signal transmission between the
radio frequency IC chip and the electrode is improved.
[0012] In the radio frequency IC device, the loop electrode is
preferably coupled to the radio frequency IC chip or the power
supply circuit board may preferably include a plurality of layers
included in a multilayer circuit board.
[0013] The radio frequency IC chip stores various pieces of
information about a product to which the radio frequency IC device
is attached, and, furthermore, may be a re-writable radio frequency
IC chip. That is, the radio frequency IC chip may have an
information processing function in addition to an RFID system
function.
[0014] According to preferred embodiments of the present invention,
an existing electrode included in a circuit board can preferably be
used as an antenna. Since a dedicated antenna is not required, a
radio frequency IC device and an apparatus including the radio
frequency IC device can be miniaturized. A resonance circuit and/or
a matching circuit included in a loop electrode and/or a power
supply circuit board may have an impedance matching function.
Accordingly, a matching section is not necessarily required.
[0015] Other features, elements, steps, characteristics and
advantages of the present invention will become more apparent from
the following detailed description of preferred embodiments of the
present invention with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1A is a plan view of a radio frequency IC device
according to a first preferred embodiment of the present
invention.
[0017] FIG. 1B is a cross-sectional view in a lengthwise direction
of the radio frequency IC device according to the first preferred
embodiment of the present invention.
[0018] FIG. 2 is a perspective view of a radio frequency IC
chip.
[0019] FIG. 3A is a plan view of a radio frequency IC device
according to a second preferred embodiment of the present
invention.
[0020] FIG. 3B is a cross-sectional view in a lengthwise direction
of the radio frequency IC device according to the second preferred
embodiment of the present invention.
[0021] FIG. 4A is a plan view of a radio frequency IC device
according to a third preferred embodiment of the present
invention.
[0022] FIG. 4B is a cross-sectional view in a lengthwise direction
of the radio frequency IC device according to the third preferred
embodiment of the present invention.
[0023] FIG. 4C is a cross-sectional view in a widthwise direction
of the radio frequency IC device according to the third preferred
embodiment of the present invention.
[0024] FIG. 5A is a plan view of a radio frequency IC device
according to a fourth preferred embodiment of the present
invention.
[0025] FIG. 5B is a cross-sectional view in a lengthwise direction
of the radio frequency IC device according to the fourth preferred
embodiment of the present invention.
[0026] FIG. 6A is a plan view of a radio frequency IC device
according to a fifth preferred embodiment of the present
invention.
[0027] FIG. 6B is a cross-sectional view in a lengthwise direction
of the radio frequency IC device according to the fifth preferred
embodiment of the present invention.
[0028] FIG. 6C is a cross-sectional view in a widthwise direction
of the radio frequency IC device according to the fifth preferred
embodiment of the present invention.
[0029] FIG. 7A is a plan view of a radio frequency IC device
according to a sixth preferred embodiment of the present
invention.
[0030] FIG. 7B is a cross-sectional view in a lengthwise direction
of the radio frequency IC device according to the sixth preferred
embodiment of the present invention.
[0031] FIG. 8A is a plan view of a radio frequency IC device
according to a seventh preferred embodiment of the present
invention.
[0032] FIG. 8B is a cross-sectional view in a lengthwise direction
of the radio frequency IC device according to the seventh preferred
embodiment of the present invention.
[0033] FIG. 9 is an exploded plan view of a circuit board of a
radio frequency IC device according to an eighth preferred
embodiment of the present invention.
[0034] FIG. 10 is an exploded plan view of a circuit board of a
radio frequency IC device according to a ninth preferred embodiment
of the present invention.
[0035] FIG. 11 is a plan view of a circuit board of a radio
frequency IC device according to a tenth preferred embodiment of
the present invention.
[0036] FIG. 12 is a plan view illustrating a main portion of a
circuit board of a radio frequency IC device according to an
eleventh preferred embodiment of the present invention.
[0037] FIG. 13 is an exploded plan view of a circuit board of a
radio frequency IC device according to a twelfth preferred
embodiment of the present invention.
[0038] FIG. 14 is an exploded plan view of a circuit board of a
radio frequency IC device according to a thirteenth preferred
embodiment of the present invention.
[0039] FIG. 15 is an exploded perspective view of a power supply
circuit board including a first exemplary resonance circuit.
[0040] FIG. 16 is a plan view of a power supply circuit board
including a second exemplary resonance circuit.
[0041] FIG. 17 is a perspective view of a mobile telephone that is
an electronic apparatus according to a preferred embodiment of the
present invention.
[0042] FIG. 18 is a diagram describing a printed circuit board
included in the mobile telephone.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0043] A radio frequency IC device and an electronic apparatus
according to preferred embodiments of the present invention will be
described below with reference to the accompanying drawings. In the
drawings, the same numerals are used for similar components and
portions so as to avoid repeated explanation.
First Preferred Embodiment
[0044] FIGS. 1A and 1B are diagrams illustrating a radio frequency
IC device according to the first preferred embodiment of the
present invention. This radio frequency IC device includes a radio
frequency IC chip 5 arranged to process a transmitted/received
signal of a predetermined frequency, a printed circuit board 20 on
which the radio frequency IC chip 5 is mounted, and a ground
electrode 21 and a loop electrode 22 which are arranged on the
printed circuit board 20. Each of the ground electrode 21 and the
loop electrode 22 is formed on the main surface of the printed
circuit board 20 preferably by applying coating of conductive paste
thereto or by etching metal foil on the printed circuit board
20.
[0045] The radio frequency IC chip 5 includes a clock circuit, a
logic circuit, and a memory circuit, and stores necessary
information. As illustrated in FIG. 2, input-output terminal
electrodes 6 and mounting terminal electrodes 7 are provided on the
undersurface of the radio frequency IC chip 5. One of the
input-output terminal electrodes 6 is electrically connected to a
connection electrode 22a disposed at one end of the loop electrode
22 via a metal bump 8, and the other one of the input-output
terminal electrodes 6 is electrically connected to a connection
electrode 22b disposed at the other end of the loop electrode 22
via the metal bump 8. A pair of connection electrodes 22c and 22d
is disposed on the printed circuit board 20. One of the mounting
terminal electrodes 7 of the radio frequency IC chip 5 is connected
to the connection electrode 22c via the metal bump 8, and the other
one of the mounting terminal electrodes 7 is connected to the
connection electrode 22d via the metal bump 8.
[0046] The loop electrode 22 is arranged near the edge of the
ground electrode 21 in the horizontal direction, whereby the loop
electrode 22 and the ground electrode 21 are coupled to each other
by electric field coupling. That is, by arranging the loop
electrode 22 near the ground electrode on the same surface, a loop
magnetic field H (denoted by a dotted line in FIG. 1A) is generated
from the loop electrode 22 in the vertical direction. The generated
loop magnetic field H enters the ground electrode 21 substantially
at right angles, so that a loop electric field E (denoted by an
alternate long and short dashed line in FIG. 1A) is excited. The
loop electric field E induces another loop magnetic field H. Thus,
the loop electric field E and the loop magnetic field H are
generated on the entire surface of the ground electrode 21, so that
a high-frequency signal is emitted. As described above, by
arranging the ground electrode 21 and the loop electrode 22 close
to each other on the same main surface while providing the
electrical isolation between them, the electromagnetic field
coupling therebetween is effectively achieved. Consequently, a
radiation characteristic is improved.
[0047] The electromagnetic coupling between the loop electrode 22
and the ground electrode 21 enables a high-frequency signal
received by the ground electrode 21 from a reader/writer to be
transmitted to the radio frequency IC chip 5 via the loop electrode
22 so as to activate the radio frequency IC chip 5, and enables a
response signal output from the radio frequency IC chip 5 to be
transmitted to the ground electrode 21 via the loop electrode 22
and then be emitted from the ground electrode 21 toward the
reader-writer.
[0048] The ground electrode 21 may preferably be defined by an
existing component included in the printed circuit board 20 of an
electronic apparatus containing the radio frequency IC device.
Alternatively, a ground electrode used for another electronic
component included in an electronic apparatus may be used as the
ground electrode 21, for example. Accordingly, in this radio
frequency IC device, a dedicated antenna is not required, and a
space is not required for the antenna. Furthermore, since a large
ground electrode 21 is used, a radiation characteristic is
improved.
[0049] By controlling the length and width of the loop electrode 22
and the space between the loop electrode 22 and the ground
electrode 21, the impedance matching between the radio frequency IC
chip 5 and the ground electrode 21 can be achieved.
Second Preferred Embodiment
[0050] FIGS. 3A and 3B are diagrams illustrating a radio frequency
IC device according to the second preferred embodiment of the
present invention. This radio frequency IC device is substantially
the same as a radio frequency IC device according to the first
preferred embodiment. The ground electrode 21 and the loop
electrode 22 are disposed on the bottom surface of the printed
circuit board 20. Connection electrodes 24a to 24d are provided on
the surface of the printed circuit board 20. The connection
electrodes 24a and 24b are electrically connected through a
via-hole conductor 23 to one end of the loop electrode 22 and the
other end of the loop electrode 22, respectively. The connection
electrodes 24a to 24d correspond to the connection electrodes 22a
to 22d illustrated in FIGS. 1A and 1B. One of the input-output
terminal electrodes 6 (see FIG. 2) is preferably electrically
connected to the connection electrode 24a via the metal bump 8, for
example, and the other one of the input-output terminal electrodes
6 is preferably electrically connected to the connection electrode
24b via the metal bump 8, for example. One of the mounting terminal
electrodes 7 (see, FIG. 2) is preferably connected to the
connection electrode 24c via the metal bump 8, for example, and the
other one of the mounting terminal electrodes 7 is preferably
connected to the connection electrode 24d via the metal bump 8, for
example.
[0051] The ground electrode 21 and the loop electrode 22 are
coupled in substantially the same manner as that described in the
first preferred embodiment. The operational advantages of a radio
frequency IC device according to the second preferred embodiment
are substantially the same as those of a radio frequency IC device
according to the first preferred embodiment. In this preferred
embodiment, a large space for another electronic component can be
obtained on the upper surface of the circuit board 20.
Third Preferred Embodiment
[0052] FIGS. 4A to 4C are diagrams illustrating a radio frequency
IC device according to the third preferred embodiment of the
present invention. In this radio frequency IC device, a loop
electrode 25 includes connection electrodes 25a and 25b disposed on
the surface of the printed circuit board 20, via-hole conductors
28, and an internal electrode 29. The loop electrode 25 is coupled
to the ground electrode 21 disposed on the bottom surface of the
printed circuit board 20 by electric field coupling. The connection
electrodes 25a and 25b are preferably electrically connected via
the metal bump 8 to the terminal electrodes 6 (see, FIG. 2).
Connection electrodes 25c and 25d are electrically connected via
the metal bump 8 to the terminal electrodes 7 (see, FIG. 2).
[0053] The loop electrode 25 is arranged near the ground electrode
21 in the vertical direction, and is coupled to the ground
electrode 21 by electric field coupling. That is, a magnetic flux
is generated from the loop electrode 25 near the surface on which
the ground electrode 21 is arranged, and an electric field that
intersects the magnetic field substantially at right angles is
generated from the ground electrode 21. As a result, an electric
field loop is excited on the ground electrode 21. The excited
electric field loop generates a magnetic field loop. Thus, the
electric field loop and the magnetic field loop are generated on
substantially the entire surface of the ground electrode 21, such
that a high-frequency signal is emitted. That is, by arranging the
loop electrode 25 near the ground electrode 21 in the vertical
direction while providing the electric isolation between the loop
electrode 25 and the ground electrode 21, the flexibility in the
placement of the loop electrode 25 can be increased.
[0054] The operation and operational advantages of a radio
frequency IC device according to the third preferred embodiment are
substantially the same as those of a radio frequency IC device
according to the first preferred embodiment. In this preferred
embodiment, since the loop electrode 25 is disposed in the printed
circuit board 20, interference caused by the penetration of a
magnetic field from the outside can be prevented. The ground
electrode 21 may be formed in the printed circuit board 20. In this
case, since a large space can be obtained on the main surface and
the bottom surface of the printed circuit board 20, another line or
another electronic component may be disposed thereon so as to
increase the packing density.
Fourth Preferred Embodiment
[0055] FIGS. 5A and 5B are diagrams illustrating a radio frequency
IC device according to the fourth preferred embodiment of the
present invention. This radio frequency IC device includes a loop
electrode 31 obtained by providing a cutout 21a at one side of the
ground electrode 21 disposed on the surface of the printed circuit
board 20. Connection electrodes 31a and 31b are electrically
connected via the metal bump 8 to one of the input-output terminal
electrodes 6 (see, FIG. 2) and the other one of the input-output
terminal electrodes 6, respectively. Connection electrodes 31c and
31d provided on the surface of the printed circuit board 20 are
electrically connected via the metal bump 8 to the mounting
terminal electrodes 7 (see, FIG. 2) of the radio frequency IC chip
5.
[0056] In the fourth preferred embodiment, the loop electrode 31 is
electrically coupled to the ground electrode 21. The radio
frequency IC chip 5 is coupled to the ground electrode 21 via the
loop electrode 31 arranged therebetween. The operation and
operational advantages of a radio frequency IC device according to
the fourth preferred embodiment are substantially the same as those
of a radio frequency IC device according to the first preferred
embodiment.
Fifth Preferred Embodiment
[0057] FIGS. 6A to 6C are diagrams illustrating a radio frequency
IC device according to the fifth preferred embodiment of the
present invention. Similar to a radio frequency IC device according
to the fourth preferred embodiment, in this radio frequency IC
device, the ground electrode 21 is electrically coupled to a loop
electrode 32. More specifically, the loop electrode 32 includes
connection electrodes 33a and 33b disposed on the surface of the
printed circuit board 20 and via-hole conductors 34. The ground
electrode 21 is disposed on the bottom surface of the printed
circuit board 20. The upper end of one of the via-hole conductors
34 is electrically connected to the connection electrode 33a, and
the upper end of the other one of the via-hole conductors 34 is
electrically connected to the connection electrode 33b. The lower
ends of the via-hole conductors 34 are electrically connected to
the ground electrode 21. The connection electrodes 33a and 33b are
electrically connected via the metal bump 8 to the terminal
electrodes 6 (see, FIG. 2) of the radio frequency IC chip 5.
Connection electrodes 33c and 33d are electrically connected via
the metal bump 8 to the terminal electrodes 7 (see, FIG. 2) of the
radio frequency IC chip 5.
[0058] In the fifth preferred embodiment, the loop electrode 32 is
electrically coupled to the ground electrode 21. The radio
frequency IC chip 5 and the ground electrode 21 are coupled to each
other via the loop electrode 32 disposed therebetween. The
operation and operational advantages of a radio frequency IC device
according to the fifth preferred embodiment are substantially the
same as those of a radio frequency IC device according to the first
preferred embodiment.
Sixth Preferred Embodiment
[0059] FIGS. 7A and 7B are diagrams illustrating a radio frequency
IC device according to the sixth preferred embodiment of the
present invention. In this radio frequency IC device, an
electromagnetic coupling module 1 is provided by mounting the radio
frequency IC chip 5 on a power supply circuit board 10. The
electromagnetic coupling module 1 is electrically connected to a
loop electrode 35 provided on the printed circuit board 20. Similar
to the loop electrode 22 described in the first preferred
embodiment, the loop electrode 35 is arranged near the ground
electrode 21 provided on the surface of the printed circuit board
20, whereby the loop electrode 35 and the ground electrode 21 are
coupled to each other by magnetic field coupling.
[0060] One of the input-output terminal electrodes 6 of the radio
frequency IC chip 5, which are illustrated in FIG. 2, and the other
one of the input-output terminal electrodes 6 are electrically
connected via the metal bump 8 to electrodes 12a and 12b (see,
FIGS. 15 and 16) provided on the surface of the power supply
circuit board 10. One of the mounting terminal electrodes 7 of the
radio frequency IC chip 5 and the other one of the mounting
terminal electrodes 7 are electrically connected via the metal bump
8 to electrodes 12c and 12d. A protection film 9 is disposed
between the surface of the power supply circuit board 10 and the
bottom surface of the radio frequency IC chip 5 so as to improve
the bonding strength between the power supply circuit board 10 and
the radio frequency IC chip 5.
[0061] The power supply circuit board 10 includes a resonance
circuit (not illustrated in FIGS. 7A and 7B) including an
inductance element. Outer electrodes 19a and 19b (see, FIGS. 15 and
16) are provided on the bottom surface of the power supply circuit
board 10, and the connection electrodes 12a to 12d (see, FIGS. 15
and 16) are provided on the surface of the power supply circuit
board 10. The outer electrodes 19a and 19b are electromagnetically
coupled to the resonance circuit included in the power supply
circuit board 10, and are electrically connected to connection
electrodes 35a and 35b of the loop electrode 35, respectively, with
an electroconductive adhesive (not illustrated), for example.
Alternatively, such electrical connection may be established by
soldering.
[0062] That is, the power supply circuit board 10 includes a
resonance circuit having a predetermined resonance frequency so as
to transmit a transmission signal of a predetermined frequency
output from the radio frequency IC chip 5 to the ground electrode
21 via the outer electrodes 19a and 19b and the loop electrode 35,
or select a received signal of a predetermined frequency from among
signals received by the ground electrode 21 and supply the selected
received signal to the radio frequency IC chip 5. Accordingly, in
this radio frequency IC device, the radio frequency IC chip 5 is
operated by a signal received by the ground electrode 21, and a
response signal output from the radio frequency IC chip 5 is
emitted from the ground electrode 21.
[0063] In the electromagnetic coupling module 1, the outer
electrodes 19a and 19b provided on the bottom surface of the power
supply circuit board 10 are coupled to the resonance circuit
included in the power supply circuit board 10 by electromagnetic
field coupling, and are electrically connected to the loop
electrode 35 that is coupled to the ground electrode 21 defining an
antenna by electric field coupling. In this preferred embodiment,
since a relatively large antenna element is not required as a
separate component, the size of the electromagnetic coupling module
1 can be reduced. Furthermore, the size of the power supply circuit
board 10 can be reduced. Accordingly, IC mounters that have been
widely used can be used to mount the radio frequency IC chip 5 on
the power supply circuit board 10. This reduces the cost of
mounting. When a frequency band to be used is changed, only the
design of the resonance circuit needs to be changed.
[0064] An inductance element alone may be used as an element
provided in the power supply circuit board 10. The inductance
element has a function of achieving the impedance matching between
the radio frequency IC chip 5 and a radiation plate (the ground
electrode 21).
Seventh Preferred Embodiment
[0065] FIGS. 8A and 8B are diagrams illustrating a radio frequency
IC device according to the seventh preferred embodiment of the
present invention. Similar to a radio frequency IC device according
to the sixth preferred embodiment, in this radio frequency IC
device, the electromagnetic coupling module 1 is formed by mounting
the radio frequency IC chip 5 on the power supply circuit board 10.
The electromagnetic coupling module 1 is electrically connected to
a loop electrode 36 provided on the printed circuit board 20.
Similar to the loop electrode 31 described in the fourth preferred
embodiment, the loop electrode 36 is obtained by forming the cutout
21a at one side of the ground electrode 21. Connection electrodes
36a and 36b are electrically connected to the outer electrodes 19a
and 19b provided on the bottom surface of the power supply circuit
board 10, with a conductive adhesive (not illustrated), for
example. In the seventh preferred embodiment, the structure and
operation of the power supply circuit board 10 are substantially
the same as those described in the sixth preferred embodiment, and
the operation of the loop electrode 36 is substantially the same as
that described in the fourth preferred embodiment.
Eighth Preferred Embodiment
[0066] FIG. 9 is an exploded view of a printed circuit board 40
included in a radio frequency IC device according to the eighth
preferred embodiment of the present invention. The printed circuit
board 40 is a multilayer board in which a plurality of dielectric
layers or magnetic layers are laminated. Loop electrodes 51A to 51D
are provided on a first layer 41A defining the surface of the
printed circuit board 40, a second layer 41B, a third layer 41C,
and a fourth layer 41D defining the bottom surface of the printed
circuit board 40.
[0067] Similar to the loop electrode described in the fourth
preferred embodiment (see, FIGS. 5A and 5B), the loop electrodes
51A to 51D are obtained by providing cutouts 50a to 50d at ground
electrodes 50A to 50D provided on the layers 41A to 41D. Connection
electrodes 52a and 52b of the loop electrode 51A provided on the
first layer 41A are respectively electrically connected to the
input-output terminal electrodes 6 of the radio frequency IC chip
5, or are electromagnetically coupled to the power supply circuit
board 10 (the electromagnetic coupling module 1). The ground
electrodes 50A to 50D may be electrically connected to each other
through via-hole conductors. An electrode functioning as an antenna
may not necessarily be a ground electrode.
[0068] Referring to FIGS. 1A and 1B, the loop electrode 22 is
preferably used so as to cause the ground electrode 21 to function
as an antenna, and the loop electrode 22 has an impedance
conversion function. More specifically, the loop electrode 22 has
an impedance between the connection electrodes 22a and 22b which is
determined by the shape of the loop. A current corresponding to a
signal transmitted from the radio frequency IC chip 5 or the power
supply circuit board 10 coupled to the connection electrodes 22a
and 22b flows along the loop.
[0069] The impedance (Z) between the connection electrodes 22a and
22b is represented by the sum of a real part and an imaginary part
(X). As the size of the loop electrode 22 is reduced, the length of
a current path is reduced. As the length of the current path is
reduced, the resistance generated at the loop electrode 22 and the
impedance (X=.omega.L) of an inductance (L) generated by a current
passing through the path are reduced. If a space for the loop
electrode 22 is reduced in accordance with the miniaturization of
an apparatus, such as a mobile telephone, for example, the
impedance of the loop electrode 22 is significantly reduced. This
produces a large impedance difference between the loop electrode 22
and a radio frequency IC chip or a power supply
(resonance/matching) circuit. Consequently, sufficient electric
power cannot be supplied from the radio frequency IC chip 5 or the
power supply circuit to a radiation plate.
[0070] In order to solve this problem, a higher impedance (Z) must
be set for the loop electrode 22, that is, the real part or the
imaginary part (X) must be increased. The eighth to thirteenth
preferred embodiments solve such a problem. Accordingly, in the
eighth preferred embodiment, the ground electrode 50A functions as
an antenna and provides the same operational advantages as those
described in the first preferred embodiment. Furthermore, in the
eighth preferred embodiment, the size of the loop electrode 51A,
which is provided on the first layer 41A and coupled to the radio
frequency IC chip 5 or the power supply circuit board 10, is
greater than that of the other loop electrodes, that is, the loop
electrodes 51B to 51D. Accordingly, the length of a current path
passing through the loop electrode 51A at the time of communication
is increased, the resistance is increased, and the real part is
increased. As a result, a higher impedance (Z) is obtained.
Ninth Preferred Embodiment
[0071] FIG. 10 is an exploded view of the printed circuit board 40
included in a radio frequency IC device according to the ninth
preferred embodiment of the present invention. A radio frequency IC
device according to the ninth preferred embodiment is substantially
the same as a radio frequency IC device according to the eighth
preferred embodiment except that connection electrodes 54a and 54b
provided on the first layer 41A and coupled to the radio frequency
IC chip 5 or the power supply circuit board 10 are electrically
connected to the loop electrode 51B provided on the second layer
41B through via-hole conductors 54c and the size of the loop
electrode 51B is greater than that of the loop electrodes 51A, 51C,
and 51D. Accordingly, the operational advantages of a radio
frequency IC device according to the ninth preferred embodiment are
substantially the same as those of a radio frequency IC device
according to the eighth preferred embodiment.
Tenth Preferred Embodiment
[0072] FIG. 11 is a diagram illustrating the printed circuit board
20 included in a radio frequency IC device according to the tenth
preferred embodiment of the present invention. A cutout 21b is
provided at the ground electrode 21 disposed on the surface of the
printed circuit board 20. In the cutout 21b, the loop electrode 31
is provided. On the inner side of the loop electrode 31, a
meandering matching electrode 37 is disposed. Connection electrodes
37a and 37b that are the ends of the matching electrode 37 are
coupled to the radio frequency IC chip 5 or the power supply
circuit board 10.
[0073] Similar to the above-described preferred embodiments, in the
tenth preferred embodiment, the ground electrode 21 functions as an
antenna, and provides substantially the same operational advantages
as those described in the first preferred embodiment. The
meandering matching electrode 37 disposed on the inner side of the
loop electrode 31 increases the length of a current path flowing
through the loop electrode 31. The resistance and the real part are
therefore increased. As a result, the impedance (Z) is increased.
The exemplary shape of the matching electrode 37 illustrated in
FIG. 11 may be changed in accordance with the shape or size of the
cutout 21b.
Eleventh Preferred Embodiment
[0074] FIG. 12 is a diagram illustrating the main portion of the
printed circuit board 20 included in a radio frequency IC device
according to the eleventh preferred embodiment of the present
invention. A radio frequency IC device according to the eleventh
preferred embodiment is substantially the same as a radio frequency
IC device according to the tenth preferred embodiment except that
the loop electrode 31 including the meandering matching electrode
37 on the inner side thereof is disposed in a cutout 21c of the
ground electrode 21 and is coupled to the ground electrode 21 by
electric field coupling in substantially the same manner as that
described in the first preferred embodiment.
[0075] Similar to the tenth preferred embodiment, in this preferred
embodiment, the connection electrodes 37a and 37b which are the
ends of the matching electrode 37 are coupled to the radio
frequency IC chip 5 or the power supply circuit board 10. The
ground electrode 21 functions as an antenna, and provides the same
operational advantages as those described in the first and tenth
preferred embodiments.
Twelfth Preferred Embodiment
[0076] FIG. 13 is an exploded view of the printed circuit board 40
included in a radio frequency IC device according to the twelfth
preferred embodiment of the present invention. Similar to a printed
circuit board described in the eighth preferred embodiment (see,
FIG. 9), the printed circuit board 40 is a multilayer board in
which a plurality of dielectric layers or a plurality of magnetic
layers are laminated. The loop electrodes 51A to 51D are provided
on the first layer 41A defining the surface of the printed circuit
board 40, the second layer 41B, the third layer 41C, and the fourth
layer 41D defining the bottom surface of the printed circuit board
40, respectively.
[0077] The loop electrodes 51A to 51D are obtained by providing the
cutouts 50a to 50d at the ground electrodes 50A to 50D provided on
the layers 41A to 41D, respectively. Connection electrodes 55a and
55b provided on the first layer 41A are respectively electrically
connected to the input-output terminal electrodes 6 of the radio
frequency IC chip 5, or are electromagnetically coupled to the
power supply circuit board 10 (the electromagnetic coupling module
1). The ground electrodes 50A to 50D may be electrically connected
to each other through via-hole conductors. An electrode functioning
as an antenna may not necessarily be a ground electrode.
[0078] Furthermore, matching electrodes 56a and 56b are disposed on
the inner side of the loop electrode 51B, and matching electrodes
57a and 57b are disposed on the inner side of the loop electrode
51C. The connection electrode 55a is connected to one end of the
matching electrode 57a through a via-hole conductor 58a, and the
other end of the matching electrode 57a is connected to one end of
the matching electrode 56a through a via-hole conductor 58b. The
other end of the matching electrode 56a is connected to an end 50Aa
of the ground electrode 50A through a via-hole conductor 58c. The
connection electrode 55b is connected to one end of the matching
electrode 57b through a via-hole conductor 58d, and the other end
of the matching electrode 57b is connected to one end of a matching
electrode 56b through a via-hole conductor 58e. The other end of
the matching electrode 56b is connected to an end 50Ab of the
ground electrode 50A through a via-hole conductor 58f.
[0079] Similar to the above-described preferred embodiments, in the
twelfth preferred embodiment, the ground electrode 50A functions as
an antenna, and provides the same operational advantages as those
described in the first preferred embodiment. Furthermore, the
length of a current path passing through the loop electrode 51A is
increased by the matching electrodes 56a and 56b, which are
disposed on the inner side of the loop electrode 51B, and the
matching electrodes 57a and 57b, which are disposed on the inner
side of the loop electrode 51C. The resistance and the real part
are therefore increased. As a result, the impedance (Z) can be
increased. In the twelfth preferred embodiment, since the matching
electrodes 56a, 56b, 57a, and 57b are included in a laminated
structure, the length of a current path can be increased even in a
small apparatus and a relatively high impedance (Z) can be
obtained.
Thirteenth Preferred Embodiment
[0080] FIG. 14 is an exploded view of the printed circuit board 40
included in a radio frequency IC device according to the thirteenth
preferred embodiment of the present invention. Similar to the
printed circuit board described in the eighth and twelfth preferred
embodiments, the printed circuit board 40 is a multilayer board in
which a plurality of dielectric layers or a plurality of magnetic
layers are laminated. The loop electrodes 51A to 51D are provided
on the first layer 41A defining the surface of the printed circuit
board 40, the second layer 41B, the third layer 41C, and the fourth
layer 41D defining the bottom surface of the printed circuit board
40, respectively.
[0081] The loop electrodes 51A to 51D are obtained by providing the
cutouts 50a to 50d in the ground electrodes 50A to 50D provided on
the layers 41A to 41D, respectively. A connection electrode 61
provided on the first layer 41A and the end 50Aa of the ground
electrode 50A are electrically connected to the input-output
terminal electrodes 6 of the radio frequency IC chip 5, or are
electromagnetically coupled to the power supply circuit board 10
(the electromagnetic coupling module 1). The ground electrodes 50A
to 50D may be electrically connected to each other through via-hole
conductors. An electrode functioning as an antenna may not
necessarily be a ground electrode.
[0082] Furthermore, matching electrodes 62 and 63 are disposed on
the inner sides of the loop electrode 51B and 51c, respectively.
The connection electrode 61 is connected to one end of the matching
electrode 63 through a via-hole conductor 64a, and the other end of
the matching electrode 63 is connected to one end of the matching
electrode 62 through a via-hole conductor 64b. The other end of the
matching electrode 62 is connected to the end 50Ab of the ground
electrode 50A through a via-hole conductor 64c.
[0083] Similar to the above-described preferred embodiments, in the
thirteenth preferred embodiment, the ground electrode 50A functions
as an antenna, and provides the same operational advantages as
those described in the first preferred embodiment. Furthermore, the
length of a current path passing through the loop electrode 51A is
increased by the matching electrodes 62 and 63 which are disposed
on the inner sides of the loop electrodes 51B and 51C,
respectively. The resistance and the real part are therefore
increased. As a result, the impedance (Z) can be increased. Similar
to the twelfth preferred embodiment, in the thirteenth preferred
embodiment, since the matching electrodes 62 and 63 are included in
a laminated structure, the length of a current path can be
increased in a small apparatus and a relatively high impedance (Z)
can be obtained.
First Example of Resonance Circuit
[0084] FIG. 15 is a diagram illustrating a first example of a
resonance circuit included in the power supply circuit board 10.
The power supply circuit board 10 is obtained by laminating,
press-bonding, and firing ceramic sheets 11A to 11H made of a
dielectric material. On the sheet 11A, the connection electrodes
12a and 12b, the electrodes 12c and 12d, and via-hole conductors
13a and 13b are provided. On the sheet 11B, a capacitor electrode
18a, conductor patterns 15a and 15b, and via-hole conductors 13c to
13e are provided. On the sheet 11C, a capacitor electrode 18b, the
via-hole conductors 13d and 13e, and a via-hole conductor 13f are
provided. On the sheet 11D, conductor patterns 16a and 16b, the
via-hole conductors 13e and 13f, and via-hole conductors 14a, 14b,
and 14d are provided. On the sheet 11E, the conductor patterns 16a
and 16b, the via-hole conductors 13e, 13f, and 14a, and via-hole
conductors 14c and 14e are provided. On the sheet 11F, a capacitor
electrode 17, the conductor patterns 16a and 16b, the via-hole
conductors 13e and 13f, and via-hole conductors 14f and 14g are
provided. On the sheet 11G, the conductor patterns 16a and 16b and
the via-hole conductors 13e, 13f, 14f, and 14g are provided. On the
sheet 11H, the conductor patterns 16a and 16b and the via-hole
conductor 13f are provided.
[0085] By laminating the sheets 11A to 11H, an inductance element
L1, an inductance element L2, a capacitance element C1, and a
capacitance element C2 are provided. The inductance element L1
includes the conductor patterns 16a that are helically connected by
the via-hole conductors 14c, 14d, and 14g. The inductance element
L2 includes the conductor patterns 16b that are helically connected
by the via-hole conductors 14b, 14e, and 14f. The capacitance
element C1 includes the capacitor electrodes 18a and 18b. The
capacitance element C2 includes the capacitor electrodes 18b and
17.
[0086] One end of the inductance element L1 is connected to the
capacitor electrode 18b through the via-hole conductor 13d, the
conductor pattern 15a, and the via-hole conductor 13c. One end of
the inductance element L2 is connected to the capacitor electrode
17 through the via-hole conductor 14a. The other ends of the
inductance elements L1 and L2 are combined on the sheet 11H, and
are then connected to the connection electrode 12a through the
via-hole conductor 13e, the conductor pattern 15b, and the via-hole
conductor 13a. The capacitor electrode 18a is electrically
connected to the connection electrode 12b through the via-hole
conductor 13b.
[0087] The connection electrodes 12a and 12b are respectively
electrically connected via the metal bump 8 to the terminal
electrodes 6 of the radio frequency IC chip 5. The electrodes 12c
and 12d are respectively connected to the terminal electrodes 7 of
the radio frequency IC chip 5.
[0088] On the bottom surface of the power supply circuit board 10,
the outer electrodes 19a and 19b are provided by applying a coating
of conductive paste thereto, for example. The outer electrode 19a
is coupled to the inductance element L (L1 and L2) by magnetic
field coupling. The outer electrode 19b is electrically connected
to the capacitor electrode 18b through the via-hole conductor 13f.
As described above, the outer electrodes 19a and 19b are
electrically connected to the connection electrodes 35a and 35b of
the loop electrode 35, or are electrically connected to the
connection electrodes 36a and 36b of the loop electrode 36.
[0089] In this resonance circuit, the inductance elements L1 and L2
are obtained by the substantially parallel arrangement of two
conductor patterns, that is, the conductor patterns 16a and 16b.
Since the line lengths of the conductor patterns 16a and 16b are
different from each other, the resonance frequencies of the
inductance elements L1 and L2 are different from one another.
Accordingly, a wider frequency band of a radio frequency IC device
can be obtained.
[0090] Each of the ceramic sheets 11A to 11H may preferably be a
ceramic sheet made of a magnetic material, for example. In this
case, the power supply circuit board 10 can be easily obtained by a
multilayer board manufacturing process including a sheet lamination
method and a thick film printing method, for example.
[0091] Each of the sheets 11A to 11H may preferably be a flexible
sheet made of a dielectric material, such as polyimide or liquid
crystal polymer, for example. In this case, the inductance elements
L1 and L2 and the capacitance elements C1 and C2 may be included in
a laminate obtained by forming an electrode and a conductor on each
of the flexible sheets using a thick film formation method and
laminating these sheets by thermocompression bonding.
[0092] In the power supply circuit board 10, the inductance
elements L1 and L2 and the capacitance elements C1 and C2 are
disposed at different locations in a perspective plan view. The
inductance elements L1 and L2 are coupled to the outer electrode
19a by magnetic field coupling. The outer electrode 19b functions
as one electrode of the capacitance element C1.
[0093] Accordingly, in the electromagnetic coupling module 1 in
which the radio frequency IC chip 5 is mounted on the power supply
circuit board 10, the ground electrode 21 receives high-frequency
signals (for example, UHF signals) emitted from a reader/writer
(not illustrated). The electromagnetic coupling module 1 causes a
resonance circuit, which is coupled to the outer electrodes 19a and
19b by magnetic field coupling and electric field coupling, to
resonate via the loop electrode 35 or 36 so as to supply only a
received signal that falls within a predetermined frequency range
to the radio frequency IC chip 5. On the other hand, predetermined
energy is extracted from the received signal, and is then used to
cause the resonance circuit to match the frequency of information
stored in the radio frequency IC chip 5 to a predetermined
frequency and then transmit the information to the ground electrode
21 via the outer electrodes 19a and 19b and the loop electrode 35
or 36. The ground electrode 21 transmits or transfers the
information to the reader/writer.
[0094] In the power supply circuit board 10, a resonance frequency
characteristic is determined by a resonance circuit including the
inductance elements L1 and L2 and the capacitance elements C1 and
C2. The resonance frequency of a signal emitted from the ground
electrode 21 is determined based on the self-resonance frequency of
the resonance circuit.
[0095] The resonance circuit also functions as a matching circuit
to perform the impedance matching between the radio frequency IC
chip 5 and the ground electrode 21. The power supply circuit board
10 may include a matching circuit separately from a resonance
circuit including an inductance element and a capacitance element
(in this sense, a resonance circuit is also referred to as a
matching circuit). If a matching circuit function is added to a
resonance circuit, the design of the resonance circuit becomes
complicated. If a matching circuit is provided separately from a
resonance circuit, they can be separately designed. The loop
electrodes 35 and 36 may have an impedance matching function or a
resonance circuit function. In this case, by designing a resonance
circuit (matching circuit) included in the power supply circuit
board 10 in view of the shape of a loop electrode and the size of a
ground electrode functioning as a radiation plate, a radiation
characteristic can be improved.
Second Example of Resonance Circuit
[0096] FIG. 16 is a diagram illustrating a second example of a
resonance circuit included in a power supply circuit board 70. The
power supply circuit board 70 is a flexible PET film on which a
helical conductor pattern 72 functioning as an inductance element L
and a capacitor electrode 73 functioning as a capacitance element C
are provided. The electrodes 12a and 12b extending from the
conductor pattern 72 and the capacitor electrode 73 are
respectively electrically connected to the terminal electrodes 6 of
the radio frequency IC chip 5. The electrodes 12c and 12d provided
on the power supply circuit board 70 are respectively electrically
connected to the terminal electrodes 7 of the radio frequency IC
chip 5.
[0097] Similar to the above-described first example of a resonance
circuit, a resonance circuit included in the power supply circuit
board 70 includes the inductance element L and the capacitance
element C, and is coupled to the electrode 35a or 36a facing the
inductance element L by magnetic field coupling and the electrode
35b or 36b facing the capacitance element C by electric field
coupling. In this second example, since the power supply circuit
board 70 is made of a flexible film, the height of the
electromagnetic coupling module 1 is reduced. In the inductance
element L, a resonance frequency can be adjusted by changing an
inductance value. Preferably, the inductance value can be changed
by changing the line width or line space of the conductor pattern
72, for example.
[0098] Similar to the first example, in the second example, the
inductance element L is obtained by helically arranging two
conductor patterns, that is, the conductor patterns 72, and
connecting them at a central portion of the helical structure. The
conductor patterns 72 have different inductance values L1 and L2.
Accordingly, similar to the first example, since the resonance
frequencies of the conductor patterns 72 can be different from one
another other, a wider usable frequency band of a radio frequency
IC device can be obtained.
Electronic Apparatus
[0099] Next, a mobile telephone will be described as an example of
an electronic apparatus according to a preferred embodiment of the
present invention. A mobile telephone 80 illustrated in FIG. 17 is
usable for a plurality of frequencies. Various signals such as a
terrestrial digital signal, a GPS signal, a WiFi signal, a CDMA
communication signal, and a GSM communication signal are input into
the mobile telephone 80.
[0100] As illustrated in FIG. 18, in a casing 81, the printed
circuit board 20 is disposed. On the printed circuit board 20, a
radio communication circuit 90 and the electromagnetic coupling
module 1 are disposed. The radio communication circuit 90
preferably includes an IC chip 91, a balun 92 included in the
printed circuit board 20, a BPF 93, and a capacitor 94, for
example. The power supply circuit board 10 on which the radio
frequency IC chip 5 is mounted is disposed on a loop electrode (for
example, the loop electrode 35 described in the sixth preferred
embodiment or the loop electrode 36 described in the seventh
preferred embodiment) coupled to the ground electrode 21 provided
on the printed circuit board 20, whereby a radio frequency IC
device is formed.
[0101] A radio frequency IC device according to the present
invention and an electronic apparatus according to the present
invention are not limited to the above-described preferred
embodiments, and various changes can be made to the present
invention without departing from the spirit and scope of the
present invention.
[0102] For example, as an electrode for transmitting and receiving
a high-frequency signal, not only a ground electrode but also
various other electrodes disposed in or on a circuit board can be
used. Furthermore, various types of resonance circuits can be used.
A material for each of the outer electrode and the power supply
circuit board which have been described in the above-described
preferred embodiments is provided only as an example. Any suitable
material having the required characteristics may be used. A power
supply circuit board may also have a radio frequency IC chip
function so as to define a radio frequency IC chip and a power
supply circuit on a single substrate. In this case, the size and
profile of a radio frequency IC device can be reduced.
[0103] In the first to fifth preferred embodiments, instead of a
radio frequency IC chip, the electromagnetic coupling module 1
described in the sixth and seventh preferred embodiments may be
used, for example.
[0104] In order to mount a radio frequency IC chip on a power
supply circuit board, another method other than a method using a
metal bump may be used. A dielectric may be disposed between the
electrode of a radio frequency IC chip and the connection electrode
of a power supply circuit board so as to provide the capacitive
coupling between these electrodes, for example. Furthermore, the
capacitive coupling between a radio frequency IC chip and a loop
electrode or between a power supply circuit board and a loop
electrode may be provided.
[0105] An apparatus including a radio frequency IC device is not
limited to a radio frequency communication apparatus, such as a
mobile telephone. Various apparatuses each provided with a circuit
board including a ground electrode, for example, home electric
appliances such as a television set and a refrigerator, may be
used.
[0106] As described above, preferred embodiments of the present
invention are useful for a radio frequency IC device including a
radio frequency IC chip and an electronic apparatus including the
radio frequency IC device, and, in particular, has an advantage of
obtaining a reduction is size and easily achieving impedance
matching without a dedicated antenna.
[0107] 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 the scope and spirit of the present invention. The scope
of the present invention, therefore, is to be determined solely by
the following claims.
* * * * *