U.S. patent application number 10/874577 was filed with the patent office on 2005-01-20 for microstrip line, resonator element, filter, high-frequency circuit and electronic device using the same.
This patent application is currently assigned to Murata Manufacturing Co., Ltd.. Invention is credited to Chikagawa, Osamu, Ida, Yutaka, Ieki, Tsutomu, Tanaka, Hiroaki, Yagi, Yoshikazu.
Application Number | 20050012572 10/874577 |
Document ID | / |
Family ID | 26608458 |
Filed Date | 2005-01-20 |
United States Patent
Application |
20050012572 |
Kind Code |
A1 |
Ida, Yutaka ; et
al. |
January 20, 2005 |
Microstrip line, resonator element, filter, high-frequency circuit
and electronic device using the same
Abstract
A microstrip line includes a strip conductor, a line electrode,
and edge electrodes provided at the edges on both sides of the line
electrode. The construction of the microstrip line greatly reduces
the edge effect of the line electrode and decreases the conductor
loss of the line electrode.
Inventors: |
Ida, Yutaka; (Yokohama-shi,
JP) ; Yagi, Yoshikazu; (Shiga-ken, JP) ; Ieki,
Tsutomu; (Yokohama-shi, JP) ; Tanaka, Hiroaki;
(Mishima-gun, JP) ; Chikagawa, Osamu; (Shiga-ken,
JP) |
Correspondence
Address: |
KEATING & BENNETT LLP
10400 Eaton Place, Suite 312
Fairfax
VA
22030
US
|
Assignee: |
Murata Manufacturing Co.,
Ltd.
Nagaokakyo-shi
JP
|
Family ID: |
26608458 |
Appl. No.: |
10/874577 |
Filed: |
June 24, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10874577 |
Jun 24, 2004 |
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10059623 |
Jan 29, 2002 |
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6798320 |
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Current U.S.
Class: |
333/238 |
Current CPC
Class: |
H01P 7/082 20130101;
H01P 3/081 20130101; H01P 3/088 20130101; H01P 11/003 20130101;
H05K 2201/037 20130101; H05K 3/107 20130101; H05K 3/4092 20130101;
H05K 1/0242 20130101; H05K 1/162 20130101; H05K 2201/09981
20130101; H01P 1/20363 20130101; H05K 1/0237 20130101; H05K
2201/09036 20130101; H05K 2201/098 20130101; H01P 1/20381
20130101 |
Class at
Publication: |
333/238 |
International
Class: |
H01P 003/08 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 29, 2001 |
JP |
2001-020436 |
Jan 9, 2002 |
JP |
2002-002445 |
Claims
1-44. (canceled).
45. A microstrip line, comprising: a dielectric substrate having a
front surface and a back surface; a ground electrode provided on
the back surface of said dielectric substrate; and a line electrode
provided on the front surface of the dielectric substrate; wherein
edge electrodes are provided at edges on both sides of the line
electrode, and said edge electrodes are arranged so as to be
inclined to the front surface of the dielectric substrate.
46. The microstrip line according to claim 45, wherein a pair of
reinforcing components made of a material having a small dielectric
loss are provided on the front surface of the dielectric substrate
to support the edge electrodes.
47. The microstrip line according to claim 46, wherein the
reinforcing components are defined by insulating films made of a
resin material.
48. The microstrip line according to claim 46, wherein the
reinforcing components are made of a ceramic material.
49. The microstrip line according to claim 46, wherein a line
groove is provided between the pair of reinforcing components, with
the front surface of the dielectric substrate defining a bottom of
the groove, said line groove includes sides that are inclined to
the front surface of the dielectric substrate, the line electrode
is provided at the bottom of the line groove, and the edge
electrodes are linked along the entire length of the line electrode
and the edges of the line electrode are located on the sides of the
line groove.
50. The microstrip line according to claim 46, wherein the edge
electrodes include a flat portion extending substantially parallel
to the front surface of the dielectric substrate along the top of
the reinforcing components.
51. The microstrip line according to claim 46, wherein a portion of
the line electrode extends between the reinforcing components and
the front surface of the dielectric substrate.
52. The microstrip line according to claim 45, wherein a flat
electrode links upper ends of the edge electrodes.
53. The microstrip line according to claim 52, wherein a space
surrounded by the line electrode, the flat electrode, and the edge
electrodes is filled with a filler having a small dielectric loss
tangent.
54. The microstrip line according to claim 45, wherein a
reinforcing layer overlaps the front surface of the dielectric
substrate and is made of a material with a small dielectric loss
tangent, such that the reinforcing layer supports the edge
electrodes.
55. A microstrip line, comprising: a dielectric substrate having a
front surface and a back surface; and a ground electrode provided
on the back surface of said dielectric substrate; wherein a pair of
reinforcing components composed of a material with a small
dielectric loss are arranged substantially parallel to each other,
a line groove is provided between the pair of reinforcing
components, with the front of the dielectric substrate defining a
bottom of the groove, and said line groove being filled in with an
electroconductive material to define a line electrode.
56. A microstrip line, comprising: a laminated substrate having a
first lamination component defined by a plurality of dielectric
layers, and a second lamination component defined by at least one
dielectric layer; and a ground electrode provided on a back surface
of the first lamination component of the laminated substrate;
wherein the second lamination component includes a strip conductor
mounted thereon and made of an electroconductive material that
fills a line groove including a line formation hole in a dielectric
sheet in which the second lamination component is provided.
57. A resonator device, including the microstrip line according to
claim 45.
58. A filter, including the resonator device according to claim
57.
59. A high frequency circuit, including the microstrip line
according to claim 45.
60. An electronic circuit, comprising: a transmission line; and a
resonator device and a filter electrically linked to said
transmission line; wherein the transmission line includes the
microstrip line according to claim 45.
61. An electronic circuit, comprising: a transmission line; and a
resonator device and a filter electrically linked to said
transmission line; wherein the transmission line and the resonator
device include a microstrip line according to claim 45.
62. An electronic circuit, comprising: a transmission line; and a
resonator device and a filter electrically linked to said
transmission line; wherein the transmission line and the filter
include a microstrip line according to claim 45.
63. A circuit module, including the electronic circuit according to
claim 60 on a dielectric substrate.
64. A communication device, including the electronic circuit
according to claim 60.
65. A communication device comprising: a circuit module including:
an electronic circuit on a dielectric substrate, including: a
transmission line; and a resonator device and a filter electrically
linked to said transmission line; wherein the transmission line and
the resonator device include a microstrip line according to claim
45.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a microstrip line, a
resonator element, a filter, and a high-frequency circuit that
utilize the microstrip line, and to an electronic circuit, circuit
module, and communications device that utilize the resonator
device, filter, and high-frequency circuit.
[0003] 2. Description of the Related Art
[0004] In small electronic devices having microwave or milliwave
circuitry, a microstrip line, as shown in FIG. 23, is generally
used as a transmission line for transmitting signals having
frequencies in the microwave or milliwave band. FIG. 23 shows a
portion of a microstrip line 1 that includes a dielectric substrate
2, a ground electrode 4 provided on the back 3 of the dielectric
substrate 2, and a flat line electrode 6 provided on the front 5 of
the dielectric substrate 2.
[0005] It is well-known that most of the line transmission loss in
the microstrip line 1 is conductor loss attributable to the
concentration of current at the edges 7 and 8 of the line electrode
6, and that an "edge effect" exists (R. A. Pucel, "Losses in
Microstrip," IEEE Trans. on MTT, Vol. MTT-16, June 1968, pp.
342-350). Conductor loss is greater when the line electrode 6 is
narrow. Consequently, it is difficult to produce an electronic
circuit having highly integrated microstrip lines 1 and very narrow
line electrodes 6.
[0006] An effective way to improve this situation is to increase
the thickness of the line electrode 6 and to reduce the current
density at the edges 7 and 8 of the line electrode 6. FIG. 24 is a
graph of the transmission characteristics (calculated) for the
microstrip line 1 when the thickness of the line electrode 6 is
varied. In FIG. 24(A), Qo is the resonance when the microstrip line
1 is cut to a specific length and made into a resonator. The value
of Qo increases as the conductor loss of the line electrode 6
decreases. Zo in FIG. 24(B) is the characteristic impedance of the
microstrip line 1, and K.sub.eff is the effective dielectric
constant of the dielectric substrate 2.
[0007] The microstrip line 1 used in the calculation of
transmission characteristics for FIG. 24 was configured such that
the dielectric constant of the dielectric substrate 2 was 38, the
thickness of the dielectric substrate 2 was 300 .mu.m, and the
width of the line electrode 6 was 20 .mu.m. As is clear from FIG.
24, when the thickness of the line electrode 6 is varied over a
range of 1 .mu.m to 25 .mu.m, the characteristic impedance Zo and
the effective dielectric constant Keff changes very little. In
contrast, the Qo value increases in proportion to the thickness of
the line electrode 6, which indicates that the conductor loss
decreases.
[0008] A problem, however, is that when the thickness of the line
electrode 6 is increased, the precision of the electrode pattern of
the electronic circuit decreases. Consequently, there have been
attempts at decreasing the edge-effect without increasing the
thickness of the line electrode 6. The following is a conventional
example of such attempts.
[0009] The microstrip line shown in FIG. 25 is discussed in
"Multilayered MMIC, V-Groove Microstrip Line Characteristics," by
Hasegawa et al., 1990 Electronic Information Communications
Society, National Fall Conference, lecture C-55. A microstrip line
10 has a V-shaped groove 13 provided on the front 12 of a
dielectric substrate 11, and a V-shaped line electrode 14 is
provided in the middle of this groove 13. As a result, the electric
field is concentrated between the V-shaped lower end portion of the
line electrode 14 and a ground electrode 16 provided on the back of
the dielectric substrate 11, thereby reducing the concentration of
current at the edges 17 and 18 of the line electrode 14.
[0010] Japanese Laid-Open Patent Application 10-313203 discloses a
microstrip line in which a groove is provided in a dielectric
substrate to reduce the transmission loss of high-frequency
signals. As shown in FIG. 26, this microstrip line 20 is designed
such that a flat line electrode 23 is provided on the front 22 of a
dielectric substrate 21, a V-shaped groove 25 is provided on the
back 24 of the dielectric substrate 21 at a location across from
the line electrode 23, and a ground electrode 26 is provided to
include the groove 25. With this configuration, an electric field
is concentrated between the line electrode 23 and the ground
electrode 26 in the V-shaped portion 27 of the ground electrode 26,
which reduces the concentration of current at the edges 28 and 29
of the line electrode 23.
[0011] Furthermore, Japanese Laid-Open Patent Application 8-288463
discloses a microstrip line in which the transmission loss of the
line is decreased by utilizing a skin effect. As shown in FIG. 27,
this microstrip line 30 includes a ground electrode 33 provided on
the back 32 of a dielectric substrate 31, and a line electrode 38
provided on the front 34 of the dielectric substrate 31, on the
sides 35 and 36 of the line electrode 38 a plurality of bumps 37
are provided. This expands the surface area of the sides 35 and 36
of the line electrode 38, thereby increasing surface current at the
sides 35 and 36 and reducing transmission loss.
[0012] Nevertheless, with the microstrip line 10 in FIG. 25, it is
difficult to form the V-shaped groove 13 with high precision in the
dielectric substrate 11, and with the microstrip line 20 in FIG.
26, it is difficult to machine the V-shaped groove 25 with high
precision in the dielectric substrate 21. Moreover, the
configurations of these microstrip lines 10 and 20 do not provide
the benefit of greatly increasing the Qo value of the microstrip
line. With the microstrip line 30 in FIG. 27, the method of forming
the line electrode 38 is complicated and the manufacturing costs
are high.
SUMMARY OF THE INVENTION
[0013] To overcome the above-described problems, preferred
embodiments of the present invention provide a microstrip line that
reduces the edge effect of the line electrode, a high frequency
circuit and a resonator device including the microstrip line that
reduces the edge effect of the line electrode, a filter including
the resonator device, an electronic circuit constituted including
this filter, a circuit module including this electronic circuit,
and a communications device including these devices.
[0014] According to a preferred embodiment of the present
invention, a microstrip line includes a dielectric substrate, a
ground electrode provided on the back of the dielectric substrate,
and a strip conductor provided on the front of the dielectric
substrate, wherein the strip conductor includes a line electrode
and edge electrodes provided at the edges on both sides of the line
electrode and along the entire length of the line electrode, and
these edge electrodes face away from the front of the dielectric
substrate.
[0015] The edge electrodes of the strip conductor function as if
the thickness of the edges of the line electrode over its entire
length is increased. That is, the edge electrodes have the same
effect as increasing the surface area of the line electrode at the
edges of the line electrode, which reduces the concentration of
high-frequency current at the edges of the line electrode, and
decreases transmission loss of the microstrip line.
[0016] The surface area at the edges of the line electrode
increases as the height of the edge electrodes increases. Thus,
high frequency current that would otherwise be concentrated at the
edges of the line electrode is dispersed, and the energy loss of
the microstrip line is greatly reduced. Therefore, by increasing
the height of the edge electrodes, the amount of high frequency
current flowing to the strip conductor is greatly increased.
[0017] Further, since the edge electrodes face away from the front
of the dielectric substrate, the edge electrodes are exposed to
air, which has a low dielectric constant. Thus, the increase in
transmission loss resulting from the edge electrodes is
minimal.
[0018] A microstrip line according to a second preferred embodiment
includes a dielectric substrate, a ground electrode provided on the
back of the dielectric substrate, and a line electrode provided on
the front of the dielectric substrate, and edge electrodes provided
at the edges on both sides of the line electrode. The edge
electrodes extend in a direction that is substantially
perpendicular to the front of the dielectric substrate.
[0019] With the microstrip line according to the second preferred
embodiment, the reduction in transmission loss in the microstrip
line is proportional to the height of the edge electrodes. However,
when short edge electrodes are provided on the line electrode, the
line electrode and edge electrodes can be provided with high
precision using thin film forming methods.
[0020] A microstrip line according to a third preferred embodiment
includes a dielectric substrate, a ground electrode provided on the
back of the dielectric substrate, and a line electrode provided on
the front of the dielectric substrate, and edge electrodes provided
at the edges on both sides of the line electrode. The edge
electrodes are preferably arranged at an angle with respect to the
front of the dielectric substrate.
[0021] With the microstrip line according to the third preferred
embodiment, even though the edge electrodes are arranged at an
angle to the front of the dielectric substrate over their entire
length, there is a reduction in the conductor loss of the
microstrip line, corresponding to the length from the front of the
dielectric substrate to the tops of the edge electrodes, and the
edge effect of the microstrip line is greatly reduced.
[0022] A microstrip line according to a fourth preferred embodiment
further includes a pair of reinforcing components made of a
material having a small dielectric loss and provided on the front
of the dielectric substrate to support the edge electrodes.
[0023] The edge electrodes are provided utilizing the sides of the
reinforcing components, and because the edge electrodes are
structurally stable, they can be made taller than the thickness of
the line electrode, allowing the effect of reducing transmission
loss to be further improved. Also, a material with a dielectric
loss that is about the same as or considerably less than the
dielectric loss of the dielectric substrate is used as an
insulating material that forms the reinforcing components, which
prevents the dielectric loss from increasing due to the addition of
the reinforcing components.
[0024] According to a fifth preferred embodiment, the reinforcing
components are preferably defined by insulating films made of a
resin material. This is particularly effective when it is necessary
to suppress an increase in dielectric loss in the microstrip line
while performing fine machining at a narrow line electrode
width.
[0025] According to a sixth preferred embodiment, the reinforcing
components may be made of a ceramic material. This is particularly
effective when a wide line electrode and tall edge electrodes are
provided to achieve a high Q value of the microstrip line. For
instance, it is possible to produce a microstrip line having a
large strip conductor in which the line electrode width is
approximately 140 .mu.m and the edge electrodes are approximately
several hundred microns tall. This further reduces transmission
loss.
[0026] The microstrip line according to a seventh preferred
embodiment further includes a line groove provided between the pair
of reinforcing components, with the front of the dielectric
substrate defining the bottom of the groove, this line groove has
sides that are substantially perpendicular to the front of the
dielectric substrate. The line electrode is provided at the bottom
of the line groove, edge electrodes are linked along the entire
length of the line electrode, and the edges of the line electrode
are provided on the sides of the line groove. This makes it easier
to form the strip conductor.
[0027] The microstrip line according to a eighth preferred
embodiment of the present invention further includes a line groove
is provided between the pair of reinforcing components, with the
front of the dielectric substrate defining the bottom of the
groove, and the line groove has sides that are inclined with
respect to the front of the dielectric substrate. The line
electrode is provided at the bottom of the line groove, edge
electrodes that are linked along the entire length of the line
electrode, and the edges of the line electrode are provided on the
sides of the line groove. This makes it easier to form the strip
conductor.
[0028] The microstrip line according to a ninth preferred
embodiment includes edge electrodes having a flat portion extending
substantially parallel to the front of the dielectric substrate
along the top of the reinforcing components. This enhances the
dimensional precision of the edge electrodes.
[0029] The microstrip line according to a tenth preferred
embodiment includes a portion of the line electrode extending
between the reinforcing components and the front of the dielectric
substrate. This enhances the dimensional precision of the line
electrode.
[0030] The microstrip line according to an eleventh preferred
embodiment further includes a flat electrode that links the upper
ends of the pair of edge electrodes. As a result, the strip
conductor has a hollow construction, and it is possible to increase
the surface current of the strip conductor.
[0031] The microstrip line according to a twelfth preferred
embodiment wherein a space surrounded by the line electrode, the
flat electrode, and the edge electrodes are filled with a filler
having a small dielectric loss tangent. This makes it easier to
produce a strip conductor having a transmission loss that is about
the same as that of the strip conductor of the eleventh preferred
embodiment, in which the interior was hollow, while still reducing
the edge effect.
[0032] The microstrip line according to a thirteenth preferred
embodiment includes a dielectric substrate and a ground electrode
provided on the back of this dielectric substrate, a pair of
reinforcing components composed of a material with a small
dielectric loss provided in parallel, a line groove provided
between the pair of reinforcing components, with the front of the
dielectric substrate defining the bottom of the groove, and this
line groove is filled in with an electroconductive material to
define a line electrode.
[0033] With this configuration, the transmission loss in the
microstrip line is reduced because the line electrode is relatively
thick, and the side walls have a larger surface area. Also, since a
pair of reinforcing components is used, a thick line electrode is
effectively and precisely provided by improving the dimensional
precision of the reinforcing components.
[0034] The microstrip line according to a fourteenth preferred
embodiment further includes a reinforcing layer that overlaps the
front of the dielectric substrate is formed from a material with a
small dielectric loss tangent to support the edge electrodes.
[0035] Again with this configuration, the reinforcing layer
performs the same function as the reinforcing components in the
fourth preferred embodiment of the present invention, and the
surface of the reinforcing layer on which the strip conductor has
not been provided is utilized to accommodate a circuit wiring
pattern and mount electronic components.
[0036] The microstrip line according to a fifteenth preferred
embodiment includes a laminated substrate having a first lamination
component including a plurality of dielectric layers, a second
lamination component including at least one dielectric layer, and a
ground electrode provided on the back of the first lamination
component of the laminated substrate, wherein the second lamination
component includes a strip conductor made of an electroconductive
material that fills a line groove defined by a line formation hole
in a dielectric sheet in which the second lamination component is
provided.
[0037] The laminated substrate is defined by dielectric layers,
such that the first and second lamination components can be made
thicker by increasing the number of layers of dielectric sheet, for
instance. In particular, when a strip conductor having a thick line
electrode is provided on the second lamination component, a thick
line electrode having outstanding dimensional precision is obtained
by providing a line formation hole corresponding to the required
shape of the strip conductor and laminating a plurality of
dielectric sheets filled with a conductive material over the first
lamination component.
[0038] A dielectric sheet is usually relatively thin, so the line
formation hole is easily formed using an NC puncher or other
suitable device. If the second lamination component is defined by a
dielectric sheet in which a line formation hole is filled with a
conductive material, anything from a thin line electrode to a line
electrode that plunges deep into the interior of the laminated
substrate can be easily provided, and as a result, it is easier to
form the strip conductor. With this configuration, the line groove
is defined by the front of the first lamination component and the
line formation hole provided in the dielectric sheet when the
second lamination component is formed, and the strip conductor ends
up being in the same form as when the line groove is filled with
the conductive material all at once.
[0039] A resonator device according to a sixteenth preferred
embodiment includes a microstrip line according to any of the first
to fifteenth preferred embodiments. Specifically, edge electrodes
are provided on a line electrode in this microstrip line, such that
less energy is consumed in the interior of the reinforcing
components which produces a resonator device having a higher Q
value for resonance.
[0040] A filter according to a seventeenth preferred embodiment
includes the resonator device according to the sixteenth preferred
embodiment of the present invention. Specifically, because a
resonator device having a high Q value for resonance is used, a
filter having sharp frequency characteristics in the pass band is
obtained.
[0041] A high frequency circuit according to an eighteenth
preferred embodiment includes a microstrip line according to any of
the first to fifteenth preferred embodiments of the present
invention. In particular, a microstrip line in which edge
electrodes are provided on a line electrode is used as the
transmission line, such that a high frequency circuit with greatly
reduced loss along the transmission line is obtained.
[0042] An electronic circuit according to a nineteenth preferred
embodiment includes a transmission line and a resonator device, and
a filter electrically linked to this transmission line. The
electronic circuit includes a microstrip line according to any of
the first to fifteenth preferred embodiments, the resonator device
according to the sixteenth preferred embodiment, and the filter
according to the seventeenth preferred embodiment.
[0043] Specifically, since a microstrip line having edge electrodes
provided on a line electrode is used as the transmission line,
there is less loss along the transmission line, and since a
resonator device with a high Q value is used as the resonator
device, and a filter with excellent characteristics is used, an
electronic circuit having outstanding performance is obtained.
[0044] A circuit module according to a twentieth preferred
embodiment includes the electronic circuit according to the
nineteenth preferred embodiment on a dielectric substrate.
Specifically, because a circuit module is produced by blocking
together electronic circuits with excellent performance, this
module is combined much more easily with other circuit modules.
[0045] A communications device according to a twenty-first
preferred embodiment includes the electronic circuit according to
the nineteenth preferred embodiment or the circuit module according
to the twentieth preferred embodiment. Specifically, because a
circuit module is used that incorporates an electronic circuit with
excellent performance, or has a block of high performance
electronic circuits, a communications device having greatly reduced
power consumption and superior communications quality is
obtained.
[0046] Other features, elements, characteristics and advantages of
the present invention will become more apparent from the following
detailed description of preferred embodiments with reference to the
attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0047] FIG. 1 is a cross sectional oblique view illustrating a
first preferred embodiment of the microstrip line according to the
present invention.
[0048] FIG. 2 shows the transmission characteristics of the
microstrip line in FIG. 1, with (A) being a graph of the Qo value
versus the height of the edge electrodes, and (B) a graph of the
characteristic impedance and effective dielectric constant versus
the height of the edge electrodes.
[0049] FIG. 3 is a cross sectional oblique view illustrating a
second preferred embodiment of the microstrip line according to the
present invention.
[0050] FIG. 4 is a cross sectional oblique view illustrating a
third preferred embodiment of the microstrip line according to the
present invention.
[0051] FIG. 5 shows the transmission characteristics of the
microstrip line in FIG. 4, with (A) being a graph of the Qo value
versus the vertical height of the edge electrodes, and (B) a graph
of the characteristic impedance and effective dielectric constant
versus the vertical height of the edge electrodes.
[0052] FIG. 6 is a cross sectional oblique view illustrating a
fourth preferred embodiment of the microstrip line according to the
present invention.
[0053] FIG. 7 is a cross sectional oblique view illustrating a
variation on the microstrip line in FIG. 4.
[0054] FIG. 8 is a graph of the Qo value versus the vertical height
of the edge electrodes in the microstrip line in FIG. 7.
[0055] FIG. 9 is a cross section of a portion of FIG. 7.
[0056] FIG. 10 is a cross sectional oblique view illustrating a
fifth preferred embodiment of the microstrip line according to the
present invention.
[0057] FIG. 11 is a cross sectional oblique view illustrating a
sixth preferred embodiment of the microstrip line according to the
present invention.
[0058] FIG. 12 is a cross sectional oblique view illustrating a
seventh preferred embodiment of the microstrip line according to
the present invention.
[0059] FIG. 13 is a cross sectional oblique view illustrating an
eighth preferred embodiment of the microstrip line according to the
present invention.
[0060] FIG. 14 is a cross sectional oblique view illustrating a
ninth preferred embodiment of the microstrip line according to the
present invention.
[0061] FIG. 15 is a cross sectional oblique view illustrating a
tenth preferred embodiment of the microstrip line according to the
present invention.
[0062] FIG. 16 is a diagram of the method for producing the
microstrip line in FIG. 15, with (A) and (B) being oblique views of
dielectric sheets, (C) a detail cross sectional oblique view of the
dielectric sheet, and (D) a detail cross sectional oblique view of
the laminated unit.
[0063] FIG. 17 is a detail cross sectional oblique view
illustrating a preferred embodiment of the resonator device
according to the present invention.
[0064] FIG. 18 is a detail cross sectional oblique view
illustrating a preferred embodiment of the filter according to the
present invention.
[0065] FIG. 19 is a detail cross sectional oblique view
illustrating another preferred embodiment of the resonator device
according to the present invention.
[0066] FIG. 20 is a detail cross sectional oblique view
illustrating another preferred embodiment of the filter according
to the present invention.
[0067] FIG. 21 is a block diagram of a preferred embodiment of the
high frequency circuit according to the present invention.
[0068] FIG. 22 is a simplified circuit diagram of a transmission
circuit illustrating an example of the high frequency circuit
according to preferred embodiments of the present invention.
[0069] FIG. 23 is a cross sectional oblique view of a conventional
microstrip line.
[0070] FIG. 24 shows the transmission characteristics of the
microstrip line in FIG. 23, with (A) being a graph of the Qo value
versus the thickness of the line electrode, and (B) a graph of the
characteristic impedance and effective dielectric constant versus
the thickness of the line electrode.
[0071] FIG. 25 is a cross sectional oblique view of another aspect
of a conventional microstrip line.
[0072] FIG. 26 is a cross sectional oblique view of yet another
aspect of a conventional microstrip line.
[0073] FIG. 27 is a cross sectional oblique view of yet another
aspect of a conventional microstrip line.
DETAILED DESCRIPTION OF PREFERREDEMBODIMENTS
[0074] Preferred embodiments of the present invention will now be
described with reference to the drawings. FIG. 1 illustrates a
first preferred embodiment of the microstrip line pertaining to the
present invention.
[0075] In FIG. 1, a microstrip line 40 preferably includes a
dielectric substrate 41, a ground electrode 43 provided over
substantially the entire back 42 of the dielectric substrate 41,
and a strip conductor 45 provided on the front 44 of the dielectric
substrate 41.
[0076] The strip conductor 45 includes a flat line electrode 46
having a slender shape and a specified width on the front 44 of the
dielectric substrate 41, and edge electrodes 48 and 49 provided at
the edges 46a and 46b on both sides of the line electrode 46 and
along the entire length thereof. The length of the line electrode
46 is determined after taking into account the wavelength
shortening effect attributable to the dielectric constant of the
dielectric substrate 41. The edge electrodes 48 and 49 are
substantially perpendicular to the front 44 of the dielectric
substrate 41 at an angle of about 90 degrees from the front 44 of
the dielectric substrate 41.
[0077] Providing the above-mentioned edge electrodes 48 and 49 has
the same effect as increasing the thickness of the edges 46a and
46b of the line electrode 46. In other words, the edge electrodes
48 and 49 disperse the high frequency current concentrated at the
edges 46a and 46b of the line electrode 46, and greatly reduce
transmission loss in the strip conductor 45.
[0078] A specific example of the microstrip line 40 will now be
described. The dielectric substrate 41 has a thickness of about 300
.mu.m and a dielectric constant of about 38. The line electrode 46
provided on the front 44 of the dielectric substrate 41 is about 5
.mu.m thick and about 20 .mu.m wide. The width (about 20 .mu.m) of
the line electrode 46 is for the portion where the line electrode
46 is in contact with the front 44 of the dielectric substrate 41
in a lateral cross section of the line electrode 46. The edge
electrodes 48 and 49 are about 5 .mu.m thick in the horizontal
direction, and their height from the front 44 of the dielectric
substrate 41 (the length of the outer surface from the front 44 to
the top) is about t .mu.m.
[0079] FIG. 2 shows the transmission characteristics of the
microstrip line 40 when the height of the edge electrodes 48 and 49
(the variable t) is varied between about 6 .mu.m and about 25
.mu.m. FIG. 2(A) shows the Qo value of the microstrip line 40,
while FIG. 2(B) shows the characteristic impedance Zo of the
microstrip line 40 and the effective dielectric constant Keff of
the dielectric substrate 41. The Qo value of the microstrip line 40
is the resonance Qo when the microstrip line 40 is cut to a
specific length and made into a resonator. The initial value of Qo
is given by the thickness of the dielectric substrate 41 and the
width of the line electrode 46.
[0080] As is clear from FIG. 2, as the height t of the edge
electrodes 48 and 49 increases, the Qo value of the microstrip line
40 increases, which indicates that there is a decrease in the
conductor loss in the strip conductor 45. Also, even when the
height t of the edge electrodes 48 and 49 is increased, the
characteristic impedance Zo of the microstrip line 40 and the
effective dielectric constant Keff of the dielectric substrate 41
remain substantially the same.
[0081] When the transmission characteristics of the microstrip line
40 shown in FIG. 2 are compared to the transmission characteristics
of the microstrip line in FIG. 24 (conventional example), the
increase in the Qo value of the microstrip lines exhibits
substantially the same tendency. We can conclude from this that the
edge electrodes 48 and 49 of the strip conductor 45 have the same
effect as increasing the thickness of the line electrode 46, and
that the edge effect of the line electrode 46 is greatly reduced by
the edge electrodes 48 and 49.
[0082] The ground electrode 43 and the strip conductor 45 are
formed by thin film formation technology using a good conductor
such as copper, silver, or gold, or other suitable material, such
that the dimensions of these components (eg, thickness, width, and
height) are set with high precision, and variances in the
characteristic impedance Zo of the microstrip line 40 and variance
in conductor loss in the microstrip line 40 are minimized during
manufacture.
[0083] FIG. 3 illustrates a second preferred embodiment of the
microstrip line pertaining to the present invention. Those
components that are the same as in the first preferred embodiment
are numbered the same, and redundant descriptions of common
portions are omitted. The characteristic feature of this preferred
embodiment is that the edge electrodes are arranged at an angle
with respect to the front of the dielectric substrate.
[0084] In FIG. 3, a strip conductor 51 of a microstrip line 50
includes a line electrode 52 and edge electrodes 53 and 54 provided
at the edges on both sides of the line electrode 52 and inclined
over their entire length. Specifically, in the cross sectional
shape of a strip conductor 56, the edge electrodes 53 and 54
provided on either side are disposed at a specific angle .theta.
with respect to the front 44 of the dielectric substrate 41 such
that they extend farther apart toward the top. The specific angle
.theta. is greater than 0 degrees but less than about 90 degrees
with respect to the front 44 of the dielectric substrate 41
(90.degree.>.theta.>0.degree.).
[0085] The length of the outer surfaces of the edge electrodes 53
and 54, that is, the length from the front 44 of the dielectric
substrate 41 to the top of the edge electrodes 53 and 54, is
preferably about t .mu.m, just as in the first preferred
embodiment. The thickness in the direction perpendicular to the
outer surface of the edge electrodes 53 and 54 is about 5 .mu.m.
The height h of the edge electrodes 53 and 54 (with respect to the
front 44 of the dielectric substrate 41) is the height when the
inclined edge electrodes 53 and 54 are projected onto a plane that
is substantially perpendicular to the front 44 of the dielectric
substrate 41 (h=t sin .theta.).
[0086] The strip conductor 51 achieves the same effect of
increasing the Qo value of the microstrip line 50 as with the
microstrip line 40 in the first preferred embodiment in FIG. 1.
[0087] FIG. 4 illustrates a third preferred embodiment of the
microstrip line according to the present invention. Those
components that are the same as in the second preferred embodiment
are numbered the same, and redundant descriptions of common
portions are omitted. The characteristic feature of this preferred
embodiment is that reinforcing components are provided to support
the strip conductor.
[0088] In FIG. 4, a microstrip line 55 includes reinforcing
components 56 and 57 that support the edge electrodes 53 and 54
from the outside along the entire length of the edge electrodes 53
and 54, and that are provided on the front 44 of the dielectric
substrate 41. Inclined surfaces 58 and 59 of the reinforcing
components 56 and 57 that are in contact with the outer surfaces of
the edge electrodes 53 and 54 are inclined at substantially the
same angle as the inclination of the edge electrodes 53 and 54. The
height of the reinforcing components 56 and 57, that is, the
thickness of the reinforcing components 56 and 57 shown between the
front 44 of the dielectric substrate 41 and the tops 61 and 62 of
the reinforcing components 56 and 57, is substantially the same
height h defined by the projected height of the edge electrodes 53
and 54. The width of the reinforcing components 56 and 57 is
determined according to the length t of the edge electrodes 53 and
54.
[0089] With the microstrip line 50 according to the second
preferred embodiment, as the length t of the edge electrodes 53 and
54 that make up the strip conductor 51 increases, it becomes more
difficult to produce the strip conductor 51, the structural
strength of the strip conductor 51 reduces.
[0090] Accordingly, with the microstrip line 55 shown in FIG. 4,
the reinforcing components 56 and 57 are formed from insulating
films provided on both sides of the strip conductor 51.
Specifically, the reinforcing components 56 and 57 have a specific
width and in the same height as the projected height of the edge
electrodes 53 and 54, are in contact with the outer surfaces of the
edge electrodes 53 and 54, and support the edge electrodes 53 and
54 from the outside of the strip conductor 51. The sides of the
reinforcing components 56 and 57 in contact with the outer surfaces
of the edge electrodes 53 and 54 are the flat, inclined faces 58
and 59.
[0091] The insulating films that define the reinforcing components
56 and 57 can be, for example, a resin material with a small
dielectric loss tangent and a low dielectric constant, such as BCB
(benzocyclobutene) or polyimide resin, or a ceramic material with a
low dielectric constant. BCB having a low dielectric constant of
about 2.3, and a ceramic material with a dielectric constant of
about 7.3 and a dielectric loss tangent of about 1.e-4 to 1.e-3 can
be used.
[0092] As mentioned above, providing the reinforcing components 56
and 57 to the microstrip line 55 greatly increases the structural
strength of the strip conductor 51. Also, since a material with a
low dielectric constant and a small dielectric loss tangent is used
for the insulating films defining the reinforcing components 56 and
57, the increase in transmission loss along the microstrip line 55
due to the reinforcing components 56 and 57 provided on both sides
of the strip conductor 51 is minimized.
[0093] Therefore, even when the reinforcing components 56 and 57
are provided on the microstrip line 55, the reduction of the
transmission loss of the microstrip line 55 achieved by providing
the edge electrodes 53 and 54 is far superior as compared with the
transmission loss of the conventional microstrip line 1 shown in
FIG. 23, to which the edge electrodes 53 and 54 are not
provided.
[0094] Additionally, in the manufacture of the microstrip line 55,
providing the reinforcing components 56 and 57 facilitates the
formation of the strip conductor 51, and particularly the formation
of the edge electrodes 53 and 54, and further, prevents damage to
the edge electrodes 53 and 54, such that the manufacturing yield of
the microstrip line 55 is greatly increased and the manufacturing
costs are greatly reduced.
[0095] With the above-described structure, when fine working
involving a narrower strip conductor 51 is required to produce the
microstrip lines 55 at a higher density, BCB or a polyimide resin,
which affords good working precision, is used for the insulating
films that define the reinforcing components 56 and 57.
[0096] FIG. 5 shows the transmission characteristics of the
microstrip line 55 when the reinforcing components 56 and 57 are
provided. These transmission characteristics are shown as the
calculated values when the edge electrodes 53 and 54 are vertical
(.theta.=90.degree.), and as the calculated values when the edge
electrodes 53 and 54 are inclined at 70 degrees
(.theta.=70.degree.) and 80 degrees (.theta.=80.degree.). In this
example, BCB insulating films are preferably used for the
reinforcing components 56 and 57 when the angle .theta. is about 70
degrees and about 80 degrees.
[0097] In the graph of FIG. 5, "height h" refers to the projected
height of the inclined edge electrodes 53 and 54. The dielectric
substrate 41 preferably has a thickness of about 300 .mu.m and a
dielectric constant of about 38, and the line electrode 52 has a
thickness of about 5 .mu.m and a width of about 20 .mu.m. The
thickness of the edge electrodes 53 and 54 is about 5 .mu.m. The
thickness of the reinforcing components 56 and 57 varies with the
angle of inclination of the edge electrodes 53 and 54, and is equal
to the projected height h of the edge electrodes 53 and 54.
[0098] As shown in FIG. 5(A), when the projected height h of the
edge electrodes 53 and 54 is varied between about 6 .mu.m and about
20 .mu.m, the Qo value of the microstrip line 55 increases along
with the length t of the edge electrodes 53 and 54 at any angle
.theta.. Furthermore, as the inclination of the edge electrodes 53
and 54 increases, the Qo value increases. In contrast, as shown in
FIG. 5(B), there is only a slight change in the characteristic
impedance Zo and the effective dielectric constant Keff.
[0099] When the microstrip line 55 is configured as described
above, with the edge electrodes 53 and 54 inclined and the strip
conductor 51 supported by the reinforcing components 56 and 57, the
transmission characteristics similar to the transmission
characteristics shown in FIG. 2 for the microstrip line 40 of the
first preferred embodiment, and the conductor loss of the
microstrip line 55 is greatly reduced.
[0100] Also, when the microstrip line 55 is produced, for example,
the line electrode 52 is formed as a thin film on the front 44 of
the dielectric substrate 41, and BCB films that define the
reinforcing components 56 and 57 are provided with the inclined
surfaces 58 and 59, which are inclined toward the edges of the line
electrode 52, after which the edge electrodes 53 and 54 are
provided using the inclined surfaces 58 and 59 of the reinforcing
components 56 and 57, which facilitates the formation of the edge
electrodes 53 and 54 and produces greater precision than when the
edge electrodes 53 and 54 are disposed vertically.
[0101] The reinforcing components 56 and 57 are provided along the
edge electrodes 53 and 54 with the microstrip line 55 described
above, however a reinforcing layer 63 is provided with the
microstrip line 60 of the fourth preferred embodiment shown in FIG.
6. This reinforcing layer 63 is defined by an insulating film with
a small dielectric loss tangent, provided as a layer over the
entire front 44 of the dielectric substrate 41 except for the
portion where the strip conductor 51 is provided, and supports the
edge electrodes 53 and 54 from the outside, similar to the
reinforcing components 56 and 57 shown in FIG. 4.
[0102] The structural strength of the edge electrodes 53 and 54 is
similarly increased by the reinforcing layer 63 in this microstrip
line 60. Further, since the reinforcing layer 63 is defined by a
material having a low dielectric constant, the effective length of
the line electrode 52 is determined by the wavelength shortening
effect attributable to the dielectric constant of the dielectric
substrate 41. Naturally, electronic components are mounted by
providing circuit wiring on the front of the reinforcing layer
63.
[0103] The microstrip line 65 in FIG. 7 is a variation on the third
preferred embodiment, the characteristic feature being that edge
electrodes 73 and 74 are much higher (longer) than the edge
electrodes 53 and 54 discussed above and shown in FIG. 4, and
reinforcing components 66 and 67 are preferably made of a ceramic
material. The dielectric substrate 41 is also preferably made of a
ceramic material, and has a thickness of, for example, about 300
.mu.m and a dielectric constant of, for example, about 30. The
dielectric constant of the ceramic material that forms the
reinforcing components 66 and 67 is preferably about 7.3.
[0104] As in the third preferred embodiment, the reinforcing
components 66 and 67 are disposed along the edges extending in the
lengthwise direction on both sides of a strip conductor 71. At
about 150 .mu.m, a line electrode 72 of the strip conductor 71 is
wider than in the third preferred embodiment. The edge electrodes
73 and 74 of the strip conductor 71 are provided on the mutually
opposed inclined surfaces 68 and 69 of the reinforcing components
66 and 67. The thickness of the reinforcing components 66 and 67,
or in other words, the projected height h1 of the edge electrodes
73 and 74 from the dielectric substrate 41, is about 100 to about
200 .mu.m, which is much greater than in the third preferred
embodiment.
[0105] Thus, if a ceramic material is used for the reinforcing
components 66 and 67, the strip conductor 71 can be configured such
that in a lateral cross section thereof, the length t of the edge
electrodes 73 and 74 away from the front 44 of the dielectric
substrate 41 is substantially equal to or greater than the width of
the line electrode 72.
[0106] Accordingly, as shown in FIG. 8, the Qo value, that is, the
conductor loss, of the microstrip line 65 is greatly improved, and
if the projected height h1 of the edge electrodes 73 and 74 is
about 200 .mu.m, for instance, the Qo value of the microstrip line
65 is improved to 1.7 times that when the edge electrodes 73 and 74
are not provided.
[0107] The method for producing the microstrip line 65 will be
briefly described with reference to FIG. 9. The pair of reinforcing
components 66 and 67, having the inclined surfaces 68 and 69, is
arranged substantially parallel at the location where the strip
conductor 71 is to be formed on the front 44 of the dielectric
substrate 41. The reinforcing components 66 and 67 are placed a
specific distance apart and with the inclined surfaces 68 and 69
facing each other. The projected height h1 of the edge electrodes
73 and 74 is determined by the thickness of the reinforcing
components 66 and 67.
[0108] When this production method is used, a line groove 70 having
a depth of from a few dozen to a few hundred microns is formed on
the front 44 of the dielectric substrate 41, with the inclined
surfaces 68 and 69 between the reinforcing component 66 and the
reinforcing component 67 serving as the groove walls, and the front
44 of the dielectric substrate 41 serving as the groove bottom. Put
another way, if the reinforcing components 66 and 67 are preferably
made of a ceramic material, the projected height h1 of the edge
electrodes 73 and 74 can be set as desired outside the range of
about 100 .mu.m to about 200 .mu.m, that is, much less than about
100 .mu.m or much greater than about 200 .mu.m. The strip conductor
71 is formed by providing a thin film of a conductor material in
this line groove 70 by vapor deposition, sputtering, electroless
plating, or other suitable method. Specifically, the line electrode
72 is provided on the front 44 of the dielectric substrate 41, and
the edge electrodes 73 and 74 are provided on the inclined surfaces
68 and 69.
[0109] FIGS. 10 and 11 illustrate fifth and sixth preferred
embodiments of the microstrip line according to the present
invention. Those components that are the same as in the third
preferred embodiment shown in FIG. 4 are numbered the same, and
redundant descriptions of common portions are omitted. The
characteristic feature of these preferred embodiments is that the
edge electrodes have a flat portion.
[0110] With the microstrip line 75 shown in FIG. 10, a strip
conductor 76 includes the line electrode 52 and the edge electrodes
53 and 54 arranged at an angle at the edges on both sides of this
line electrode 52. The characteristic feature of the fifth
preferred embodiment is that flat portions 77 and 78 are provided
at the tops of the edge electrodes 53 and 54. These flat portions
77 and 78 are provided on the upper surfaces of the reinforcing
components 56 and 57 over the entire length of the edge electrodes
53 and 54, extending substantially parallel to the front 44 of the
dielectric substrate 41 from the tops of the edge electrodes 53 and
54 toward the reinforcing components 56 and 57. This enables the
inclined portions of the edge electrodes 53 and 54 to be produced
with outstanding dimensional precision.
[0111] Also, when the edge electrodes 53 and 54 are provided, a
strip conductor 81 is configured such that the location where the
edge electrodes 53 and 54 are provided is slightly to the inside of
edges 82 and 83 on both sides of the line electrode 52, as is the
case with the microstrip line 80 shown in FIG. 11. With this
configuration, a portion of the line electrode 52 is between the
insulating films that define the reinforcing components 56 and 57
and the front 44 of the dielectric substrate 41.
[0112] This configuration of the microstrip line 80 requires
outstanding dimensional precision of the width of the line
electrode 52, and thus, the line electrode 52 is provided on the
front 44 of the dielectric substrate 41 at the beginning of the
manufacturing process. Then, the reinforcing components 56 and 57
are preferably formed from insulating films of BCB resin on both
sides of the line electrode 52, after which the inclined surfaces
of the reinforcing components 56 and 57 are utilized in forming the
edge electrodes 53 and 54. This method greatly improves the
dimensional precision of both the line electrode 52 and the edge
electrodes 53 and 54.
[0113] FIGS. 12 and 13 illustrate seventh and eighth preferred
embodiments of the microstrip line according to the present
invention. Those components that are the same as in the third
preferred embodiment shown in FIG. 4 are numbered the same, and
redundant descriptions of common portions are omitted. The
characteristic feature of these preferred embodiments is a flat
electrode provided above the line electrode.
[0114] With the microstrip line 85 shown in FIG. 12, the strip
conductor 86 includes the line electrode 52 provided on the front
44 of the dielectric substrate 41, the edge electrodes 53 and 54
that are linked at an angle to the edges of this line electrode 52,
and the flat electrode 87 provided at the upper end of the edge
electrode 53 and the upper end of the edge electrode 54, linking
the edge electrodes 53 and 54 over their entire length, and
substantially parallel to the line electrode 52. The inside area
surrounded by the line electrode 52, the edge electrodes 53 and 54,
and the flat electrode 87 is empty space.
[0115] With this configuration, the internal space in a strip
conductor 91 surrounded by the line electrode 52, the edge
electrodes 53 and 54, and the flat electrode 87 is filled with a
filler 92 having a small dielectric loss tangent, such as the BCB
resin or other resin material that defines the reinforcing
components 56 and 57, a ceramic material, or another suitable
insulating substance. The effect of this configuration is that the
flat electrode 87 can be formed after the line electrode 52 and the
edge electrodes 53 and 54 have been formed and filled with the
filler, which facilitates production of the strip conductor 91.
[0116] FIG. 14 illustrates the ninth preferred embodiment of the
microstrip line according to the present invention. Those
components that are the same as in the preferred embodiment
illustrated in FIG. 9 are numbered the same, and redundant
descriptions of common portions are omitted. The characteristic
feature of this preferred embodiment is that, unlike in the
preferred embodiments described above, the line electrode of the
microstrip line is much thicker.
[0117] A strip conductor 96 of a microstrip line 95 is provided
using the line groove 70 shown in FIG. 9. Specifically, a line
electrode 97 that defines the strip conductor 96 is provided having
an increased thickness by filling in the line groove 70 with a
conductive material. The thickness of the line electrode 97 is
greater than the thickness of the line electrodes 46, 52, and 72 in
the preferred embodiments described above. Edge electrodes are
therefore unnecessary. The thickness of the line electrode 97 is
determined by the thickness of the pair of reinforcing components
66 and 67.
[0118] The effect of this configuration is that the edge portions
of the line electrode 97, that is, the sides of the line electrode
97, have a greater surface area and high frequency current is more
evenly dispersed, such that there is less conductor loss in the
line electrode 97, and the transmission loss along the microstrip
line 95 is greatly reduced.
[0119] FIG. 15 illustrates a tenth preferred embodiment of the
microstrip line pertaining to the present invention. The
characteristic feature of this preferred embodiment is that the
microstrip line includes a laminated substrate.
[0120] A microstrip line 100 includes a strip conductor 104
provided on a laminated substrate 101 including a first lamination
component 102 and a second lamination component 103. The first
lamination component 102 defines the dielectric substrate, and is
made, for example, by laminating a plurality of dielectric sheets
(green sheets) such that the thickness after baking will be about
60 .mu.m. These dielectric sheets are formed, for example, from a
ceramic material with a high dielectric constant (such as a
dielectric constant of about 30). More specifically, the first
lamination component 102 is produced by laminating five dielectric
sheets such that the substrate thickness after baking is about 300
.mu.m. The ground electrode 43 is provided on the back of the first
lamination component 102.
[0121] The second lamination component 103 is a reinforcing layer,
and is formed, for example, by laminating one or more dielectric
sheets (green sheets) composed of a dielectric material over the
front of the first lamination component 102 such that the thickness
of the sheets after baking is about 60 .mu.m. The dielectric sheets
of the second lamination component 103 are ceramic sheets having a
low dielectric constant of about 7.3, for example. A line formation
hole 106, such as a slot, is provided in the dielectric sheets such
that the width and length will match the designed shape of the
strip conductor 104 after shrinkage caused by baking. This line
formation hole 106 is filled with a conductive material, and this
conductive portion defines a line electrode 105.
[0122] Again with the above configuration, when the thickness of
the line electrode 105 is increased, the Qo value of the microstrip
line 100 increases, just as with the characteristics of the Qo
value shown in FIG. 8. When the thickness of the line electrode 105
of the second lamination component 103 is increased, a plurality of
dielectric sheets are laminated. In this case, the lamination is
performed such that the conductive portion filling the line
formation hole 106 is aligned with outstanding precision in the
upper and lower dielectric sheets, or in other words, such that the
portions of the dielectric sheets including the line formation hole
106 will line up in the upper and lower layers. Therefore, filling
the line formation hole 106 with a conductive material and
laminating dielectric sheets enables the thickness of the line
electrode 105 to be varied as desired, and furthermore produces a
line electrode 105 having outstanding dimensional precision. Put
another way, it is easy to produce a strip conductor 104 in which
the cross section of the line electrode 105 has a high aspect
ratio.
[0123] The method for manufacturing the microstrip line 100, and
particularly the method for producing the second lamination
component 103 portion, will now be described with reference to FIG.
16. First, the dielectric sheet (green sheet) 110 shown in FIG.
16(A) is produced. Suitable amounts of binder, plasticizer, and
solvent are added to a ceramic or glass ceramic powder, and these
are kneaded to produce a slurry. The inorganic material used as the
binder is preferably a low-loss material with a low baking
temperature, whose main components are a material based on
BaO--TiO.sub.2-rare earth oxide, and borosilicate glass, such as
Mg--Al--Si--B--O. The slurry obtained in this manner is applied by
doctor blade to form the dielectric sheet 110 having the desired
thickness.
[0124] We will assume here that the shrinkage of the dielectric
sheet 110 in the primary dimension during baking is about 20%. The
shrinkage of a dielectric sheet during baking varies with the
conditions under which the dielectric sheet is produced, the baking
conditions, and so forth, so the shrinkage is not limited to about
20%, and should be set as dictated by the production
conditions.
[0125] The line formation hole 106 having a width of about 250
.mu.m is formed with an NC puncher in and completely through this
dielectric sheet 110. The length of the line formation hole 106 is
the length required for design purposes. In addition to punching
with an NC puncher, laser punching, mold tool punching, mechanical
cutting, or another suitable method can be used to form the line
formation hole 106.
[0126] The line formation hole 106 in the dielectric sheet 110 is
filled with a silver-based conductive paste (the conductive
material) as shown in FIG. 16(C). This filling forms a conductive
component 112 of the same thickness as the dielectric sheet 110 in
the line formation hole 106 portion. The conductive paste is not
limited to a silver-based material, and can also be any other
low-resistance metal material based on gold, copper, or other
suitable material. After this, the dielectric sheet 110 in which
the conductive component 112 has been formed is dried for about 15
minutes at about 60.degree. C.
[0127] These dried dielectric sheets 110 are used to produce a
laminated unit 115 in which reinforcing laminates 114 that define
the second lamination component 103 are provided over a substrate
laminate 113 that define the first lamination component 102, as
shown in FIG. 16(D). When the thickness of the line electrode 105
is the same (about 180 .mu.m) as the thickness of the strip
conductor 104, for instance, three 75 .mu.m dielectric sheets 110
in which the conductive component 112 has been formed are laminated
by press bonding over the substrate laminate 113. At this stage of
the process, the substrate laminate 113 is in a state in which
dielectric sheets 116 made of dried ceramic material have been
press bonded and laminated, and a conductor layer 117 defining the
ground electrode 43 is applied to the lowermost dielectric sheet
116 by screen printing using a silver-based conductive paste.
[0128] The laminated unit 115 configured as above is baked for
about 1 hour at a temperature of about 900.degree. C. to obtain a
laminated ceramic sinter. This baking sinters and integrates the
various layers of conductive component 112 in the reinforcing
laminate 114, and completes the microstrip line 100 equipped with
the reinforcing laminate 114. The line electrode 105 of the strip
conductor 104 has a substantially rectangular cross section with a
width of about 200 .mu.m and a thickness of about 180 .mu.m, the
bottom 107 of the line electrode 105 is in contact with the first
lamination component 102 over a width of about 200 .mu.m, and the
side surfaces 108 and 109 are in contact with the second lamination
component 103, which is about 180 .mu.m thick.
[0129] With the above method for producing a microstrip line, the
thickness of the line electrode 105 can be increased as desired in
about 60 .mu.m increments by laminating more dielectric sheets 110
in which the conductive component 112 has been formed, and this
increases the surface area of the side surfaces 108 and 109 of the
line electrode 105, and reduces the transmission loss along the
microstrip line 100. Also, since the line electrode 105 is made
using the line formation holes 106 provided in the dielectric
sheets 110, the dimensional precision is outstanding, and the line
formation holes 106 are formed by NC punching or another simple
method, which greatly reduces the manufacturing costs.
[0130] The manufacturing method discussed above only involves the
production of a microstrip line, but internal wiring or internal
electrodes can also be provided, as needed, between the layers of
the laminated unit 115, and via-hole conductors can be formed to
link the internal wiring or internal electrodes to form an inductor
or a capacitor. In this case, the via-holes are made in the
dielectric sheets 110 at the same time the line formation holes 106
are formed, and the via-hole conductors are formed by filling the
via-holes with a conductive paste at the same time the conductive
component 112 is formed. This method provides outstanding design
freedom of circuit substrates that feature microstrip lines.
[0131] Also, if the line electrode 105 is to be thinner than the
above-mentioned dielectric sheet 110, the thickness of the
dielectric sheet 110 is reduced. For instance, the baked line
electrode 105 can be formed in units of about 40 .mu.m of thickness
by changing the thickness of the dielectric sheets 110 to about 50
.mu.m. The second lamination component 103 may also be formed by
laminating one or more layers of organic insulating film using BCB,
a polyimide resin, or other suitable material. The manufacturing
method described above is not used when an organic insulating film
is used. A pre-baked first lamination component 102 is used
instead.
[0132] FIG. 17 illustrates a preferred embodiment of the resonator
device according to the present invention. Those components that
are the same as in the fifth preferred embodiment shown in FIG. 10
are numbered the same, and redundant descriptions of common
portions are omitted.
[0133] As shown in FIG. 17, a resonator device 120 includes the
microstrip line 75 shown in FIG. 10. The resonator device 120 is
provided on the front 44 of the dielectric substrate 41, and
includes a strip conductor 121 having a length of approximately
one-half the wavelength of the resonance frequency fo that will be
used, electrode supports 122 and 123 are disposed on both sides
(laterally) of this strip conductor 121, have a trapezoidal cross
sectional shape, and are slightly longer than the overall length of
the strip conductor 121, and link electrodes 124 and 125 provided
to the front 44 in proximity to the ends of the strip conductor 121
in its lengthwise direction.
[0134] With the above configuration, the strip conductor 121
includes a resonance electrode 126 provided on the front 44 of the
dielectric substrate 41, and edge electrodes 128 and 129 provided
on both sides in the lateral direction of this resonance electrode
126. The length of the resonance electrode 126 is approximately
one-half the wavelength of the resonance frequency fo. Further, the
edge electrodes 128 and 129 are provided along the entire length of
the resonance electrode 126 (the edges extending in the lengthwise
direction), supported by the inclined faces of the electrode
supports 122 and 123. Flat portions 130 and 131 extending to the
upper surfaces of the electrode supports 122 and 123 are provided
to the tops of the edge electrodes 128 and 129.
[0135] The above configuration produces a resonator device 120
having a high Qo value during resonance. This Qo value is
determined from the following equation.
Q=2.pi.fo.times.(stored energy of resonance circuit)/(energy lost
in resonance circuit in 1 second)
[0136] Here, fo is the resonance frequency of the resonator device
120, and the resonance circuit is the equivalent resonance circuit
corresponding to the resonator device 120.
[0137] It can be seen from this equation that the Qo value of the
resonance circuit increases in inverse proportion to the energy
loss in the resonance circuit. Specifically, the resonator device
120 includes the edge electrodes 128 and 129 provided to the
resonance electrode 126, which lessens the concentration of current
at the edges of the resonance electrode 126, decreases the
conductor loss of the resonance electrode 126, and reduces the
energy loss of the resonance circuit. Also, much less variance in
the Qo value occurs during the manufacture of the resonator device
120 as described above, such that the manufacturing yield is
greatly increased, and, as a result, the manufacturing costs are
greatly reduced.
[0138] The resonator device 120 described above features the
microstrip line 75 shown in FIG. 10, however, the resonator device
can be constructed using the microstrip lines according to any of
the other preferred embodiments.
[0139] FIG. 18 illustrates a preferred embodiment of the filter
according to the present invention. Those components that are the
same as in the preferred embodiment shown in FIG. 17 are numbered
the same, and redundant descriptions of common portions are
omitted. The characteristic feature of this preferred embodiment is
that four resonator devices are provided.
[0140] As shown in FIG. 18, a filter 135 is provided with four
resonator devices 120 that are configured as shown in FIG. 17, and
includes five electrode supports 136 to 140 disposed substantially
parallel to each other and equidistantly spaced on the front 44 of
the dielectric substrate 41, four strip conductors 141 to 144
arranged in a lateral row and provided between the adjacent
electrode supports 136 to 140, and linking electrodes 145 and 146
that extend in the arrangement direction on the electrode supports
136 and 140 and connect to a flat component 130 of the strip
conductor 141 located at the beginning of the lateral row, and to a
flat component 131 of the strip conductor 144 located at the end of
this row.
[0141] The lateral row of strip conductors 141 to 144 share the
electrode supports 137, 138, and 139. For instance, the edge
electrodes 128 and 129 of the adjacent strip conductors 142 and 143
are provided on inclined surfaces disposed at substantially the
same inclination angle as the shared electrode support 138, and the
flat components 130 and 131 of the strip conductors 142 and 143 are
provided on the upper surface of the shared electrode support
138.
[0142] The various strip conductors 141 to 144 have a length of
approximately one-half the wavelength at the frequency fo being
used. The flat components 130 and 131 of the strip conductors 141
to 144 are disposed in proximity and regularly spaced on the upper
surface of the electrode supports, 137, 138, and 139.
[0143] With the above configuration, if the coupling electrode 145
is used as the input side and the coupling electrode 146 as the
output side, for example, when high-frequency current with a
frequency of fo is input to the coupling electrode 145, the
adjacent strip conductors 141 to 144 are magnetically coupled
together, and the various strip conductors 141 to 144 resonate in a
coupled mode.
[0144] As a result, the filter 135 functions as a bandpass filter
that transmits high-frequency signals through a frequency band
centered around the frequency fo. This filter 135 produces better
filter performance because of the high resonance Q value in the
four strip conductors 141 to 144, and the filter loss is also
greatly reduced.
[0145] FIG. 19 illustrates another preferred embodiment of the
resonator device according to the present invention. Those
components that are the same as in the tenth preferred embodiment
shown in FIG. 15 are numbered the same, and redundant descriptions
of common portions are omitted. The characteristic feature of the
resonator device 150 in this preferred embodiment is the laminated
substrate.
[0146] In FIG. 19, the resonator device 150 includes the microstrip
line 100 shown in FIG. 15. A strip conductor 151 of the resonator
device 150 is formed using the production method shown in FIG. 16,
and using the conductive component 112 filling the slender line
formation hole 106 provided in the second lamination component 103
of the laminated substrate 101. This strip conductor 151 defines a
resonance electrode 152 of the resonator device 150.
[0147] The thickness of the resonance electrode 152 is determined
by the number of layers of the conductive component 112, and
coupling electrodes 155 and 156 are provided on both sides in the
lengthwise direction of the strip conductor 151, on the front of
the second lamination component 103 of the laminated substrate 101,
and in contact with the edges of the line formation hole 106.
[0148] This resonator device 150 operates in the same manner as the
resonator device 120 shown in FIG. 17. Specifically, conductor loss
of the resonance electrode 152 is greatly reduced by the sides 153
and 154 of the resonance electrode 152, such that the resulting
resonator device has a high Q value.
[0149] FIG. 20 illustrates another preferred embodiment of the
filter according to the present invention. Those components that
are the same as in the preferred embodiment illustrated in FIG. 19
are numbered the same, and redundant descriptions of common
portions are omitted. The characteristic feature of the filter 160
of this preferred embodiment is that three resonator devices are
provided on a laminated substrate.
[0150] As shown in FIG. 20, three line formation holes 161, 162,
and 163 are provided in a lateral row, equidistantly spaced and
substantially parallel to the drawing direction, on the second
lamination component 103 of the laminated substrate 101. Strip
conductors 164, 165, and 166 are formed by filling in these line
formation holes 161, 162, and 163, respectively, with a conductive
paste. Coupling electrodes 167 and 168 are provided on the front of
the second lamination component 103 of the laminated substrate
101.
[0151] The coupling electrode 167 is connected to the strip
conductor 164 located at the beginning of the strip conductors 164,
165, and 166 arranged in a lateral row, while the coupling
electrode 168 is connected to the strip conductor 166 located at
the end of this lateral row.
[0152] With this configuration, if the coupling electrode 167 is
used as the input side and the coupling electrode 168 as the output
side, for example, when high-frequency current is input to the
coupling electrode 167, just as with the filter 135 shown in FIG.
18, the resonance electrodes 152 of the adjacent strip conductors
164, 165, and 166 are magnetically coupled together, and the
various strip conductors 164, 165, and 166 resonate in a coupled
mode.
[0153] Here, the strip conductors 164, 165, and 166 are each
excited with very low energy loss, just as with the resonator
device 150 in FIG. 19, such that the Q value is high and the
resulting filter provides outstanding performance.
[0154] FIG. 21 is a block diagram of a preferred embodiment of a
communications device according to the present invention, such as a
cellular telephone or other wireless communications device.
Specifically, a communications device 170 includes a high frequency
circuit 171, a signal processing circuit 172, and an antenna 173.
The antenna 173 is connected to the input terminal of the high
frequency circuit 171, and the signal processing circuit 172 is
connected to the output terminal of the high frequency circuit
171.
[0155] The high frequency circuit 171 includes a reception circuit
that amplifies the wireless signal (RF signal) received by the
antenna 173 and converts it into a baseband signal (IF signal), and
a transmission circuit that converts the IF signal output from the
signal processing circuit 172 into an RF signal, amplifies the
signal, and emits it from the antenna 173 as radio waves. The
high-frequency transmission circuit in the high frequency circuit
171 includes the microstrip line of various preferred embodiments
of the present invention described above. This greatly reduces
transmission loss along the high frequency circuit 171, greatly
improves the performance of the communications device, and greatly
reduces power consumption.
[0156] A specific example of the transmission circuit of the high
frequency circuit 171 will be described through reference to FIG.
22. A transmission circuit 180 includes an input terminal 181 for
inputting an IF signal from the signal processing circuit 172, a
mixer 182 that is connected to the input terminal 181 and converts
an IF signal into an RF signal, a local oscillator 183 for
supplying a carrier signal to the mixer 182, a power amplifier 184
for boosting the power of the RF signal outputted from the mixer
182, a bandpass filter 185 for removing unnecessary signals from
the amplified RF signal, and an output terminal 186 for outputting
the RF signal from the bandpass filter 185 to the antenna 173.
[0157] In the above transmission circuit 180, the IF signal input
to the input terminal 181 is converted into an RF signal by the
mixer 182. This RF signal is amplified by the power amplifier 184
and passes through the bandpass filter 185, after which it is
emitted from the antenna 173 as radio waves.
[0158] In the above-mentioned transmission circuit 180, the
microstrip lines 40, 50, 55, 60, 65, 75, 100, and the resonator
devices 120 and 150 of various preferred embodiments of the present
invention can be used for the local oscillator 183, the microstrip
lines 40, 50, 55, 60, 65, 75, 100 of the present invention can be
used for the power amplifier 184, and the filters 135 and 160 of
the present invention can be used for the bandpass filter 185.
Using these components greatly improves the performance of the
local oscillator 183, increases the gain, lowers the noise, and
reduces the power consumption of the power amplifier 184, and
further, greatly improves the performance and reduces loss in the
bandpass filter 185.
[0159] The above-described high frequency circuit 171 is produced,
for example, by blocking together electronic circuits, such as
reception circuits and transmission circuits into a circuit module.
Specifically, a circuit module is produced by cutting the
dielectric substrate 41 down to a small surface area, and forming
only the transmission circuit 180 shown in FIG. 22 on this small
substrate. This configuration allows the reception circuit, which
must have low noise, and the transmission circuit, which must have
high power, to be separated.
[0160] The high frequency circuit, electronic circuit, and circuit
module of various preferred embodiments of the present invention
are not limited to a communications device, and can be included in
a variety of electronic devices in which one of the microstrip
lines, resonator devices, or filters of the present invention are
used.
[0161] With the microstrip line of various preferred embodiments of
the present invention, edge electrodes are provided along the
entire length of the line electrode at the edges thereof, and the
high frequency current that would otherwise concentrate at the
edges of the line electrode is dispersed, such that the edge effect
of the line electrode is greatly reduced, and conductor loss in the
line electrode is also greatly reduced.
[0162] When the microstrip line of preferred embodiments of the
present invention is used, a resonator device with a greatly
increased Q value is obtained, and the use of this resonator device
greatly improves the performance and greatly reduces the loss of a
filter, and also affords a high frequency circuit in which the
transmission loss of the transmission line is greatly reduced.
[0163] Furthermore, using the microstrip line, resonator device, or
filter of preferred embodiments of the present invention provides
an electronic circuit or circuit module having outstanding
performance, and with a communications device, the communications
quality is greatly improved and power consumption is greatly
reduced.
[0164] While preferred embodiments of the 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 invention. The scope of the
invention, therefore, is to be determined solely by the following
claims.
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