U.S. patent application number 09/853756 was filed with the patent office on 2001-11-29 for non-reciprocal circuit element and millimeter-wave hybrid integrated circuit board with the non-reciprocal circuit element.
This patent application is currently assigned to TDK CORPORATION. Invention is credited to Hasegawa, Makoto, Henmi, Sakae, Kurahashi, Takahide, Miura, Taro, Ohata, Hidenori, Suzuki, Kazuaki.
Application Number | 20010045872 09/853756 |
Document ID | / |
Family ID | 17637884 |
Filed Date | 2001-11-29 |
United States Patent
Application |
20010045872 |
Kind Code |
A1 |
Miura, Taro ; et
al. |
November 29, 2001 |
Non-reciprocal circuit element and millimeter-wave hybrid
integrated circuit board with the non-reciprocal circuit
element
Abstract
A non-reciprocal circuit element includes a microstrip
TM.sub.n10 resonator (n is a positive integer) with a metal disk
and branches projecting from the metal disk in a trigonally
symmetric structure, and a ferrite magnetic body spontaneously
magnetized and coaxially disposed on the microstrip TM.sub.n10
resonator. The metal disk and the branches are formed on a
non-magnetic dielectric board having a ground conductor on its
bottom face. The ferrite magnetic body is arranged so that a
position of an electric field node matches to one of the
branches.
Inventors: |
Miura, Taro; (Tokyo, JP)
; Hasegawa, Makoto; (Fukuoka, JP) ; Kurahashi,
Takahide; (Tokyo, JP) ; Ohata, Hidenori;
(Tokyo, JP) ; Henmi, Sakae; (Tokyo, JP) ;
Suzuki, Kazuaki; (Tokyo, JP) |
Correspondence
Address: |
ARMSTRONG,WESTERMAN, HATTORI,
MCLELAND & NAUGHTON, LLP
1725 K STREET, NW, SUITE 1000
WASHINGTON
DC
20006
US
|
Assignee: |
TDK CORPORATION
Tokyo
JP
|
Family ID: |
17637884 |
Appl. No.: |
09/853756 |
Filed: |
May 14, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09853756 |
May 14, 2001 |
|
|
|
PCT/JP00/06821 |
Oct 2, 2000 |
|
|
|
Current U.S.
Class: |
333/1.1 ;
333/24.2 |
Current CPC
Class: |
H05K 1/0243 20130101;
H01P 1/36 20130101; H05K 1/181 20130101; H01P 1/38 20130101 |
Class at
Publication: |
333/1.1 ;
333/24.2 |
International
Class: |
H01P 001/32 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 10, 1999 |
JP |
11-281349 |
Claims
What is claimed is:
1. A non-reciprocal circuit element, comprising: a microstrip
TM.sub.n10 resonator (n is a positive integer) with a metal disk
and branches projecting from said metal disk in a trigonally
symmetric structure, said metal disk and said branches being formed
on a non-magnetic dielectric board having a ground conductor on its
bottom face; and a ferrite magnetic body spontaneously magnetized
and coaxially disposed on said microstrip TM.sub.n10 resonator,
said ferrite magnetic body being arranged so that a position of an
electric field node matches to one of said branches.
2. The element as claimed in claim 1, wherein said ferrite magnetic
body has a shape of a disk or a cylinder.
3. The element as claimed in claim 1, wherein said TM.sub.n10
resonator is a TM.sub.m10 resonator (m is a positive integer of 2
or more).
4. The element as claimed in claim 3, wherein said metal disk is
partially removed around a central axis of said TM.sub.m10
resonator.
5. The element as claimed in claim 4, wherein said ferrite magnetic
body is partially removed around the central axis of said
TM.sub.m10 resonator.
6. The element as claimed in claim 5, wherein said ferrite magnetic
body has a hole whose inner wall is metallized, said hole being
formed by partially removing said ferrite magnetic body around the
central axis.
7. The element as claimed in claim 1, wherein at least top and
bottom faces of said ferrite magnetic body are metallized.
8. The element as claimed in claim 1, wherein said TM.sub.n10
resonator is a TM.sub.110 resonator, and wherein a Faraday rotator
with a ferrite cylinder that has a metallized free end face and a
propagation length of one wavelength.
9. The element as claimed in claim 8, wherein a non-magnetic
dielectric body is coupled to said ferrite cylinder.
10. The element as claimed in claim 9, wherein a dielectric
constant of said non-magnetic dielectric body is selected such that
said ferrite cylinder and said non-magnetic dielectric body are
equal to each other in characteristic impedance.
11. The element as claimed in claim 1, wherein 1/4 wavelength
impedance matching elements are connected to said branches,
respectively.
12. The element as claimed in claim 1, wherein one terminal is
connected to a matching resistor and other two terminals are formed
as input and output terminals.
13. The element as claimed in claim 1, wherein said dielectric
board is a millimeter-wave hybrid integrated circuit board.
14. A millimeter-wave hybrid integrated circuit board having at
least one non-reciprocal circuit element, said element comprising:
a microstrip TM.sub.n10 resonator (n is a positive integer) with a
metal disk and branches projecting from said metal disk in a
trigonally symmetric structure, said metal disk and said branches
being formed on a non-magnetic dielectric board having a ground
conductor on its bottom face; and a ferrite magnetic body
spontaneously magnetized and coaxially disposed on said microstrip
TM.sub.n10 resonator, said ferrite magnetic body being arranged so
that a position of an electric field node matches to one of said
branches.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This is a continuation of International Application
PCT/JP00/06821, with an international filing date of Oct. 2,
2000.
FIELD OF THE INVENTION
[0002] The present invention relates to a non-reciprocal circuit
element used for a millimeter-wave hybrid integrated circuit board
provided with an active element such as a semiconductor element
mounted thereon, and a millimeter-wave hybrid integrated circuit
board with the non-reciprocal circuit element.
DESCRIPTION OF THE RELATED ART
[0003] In an active element mounted on a circuit such as a
millimeter-wave circuit, transmitting radio wave having an
extremely short wavelength, the following problems have
occurred.
[0004] (1) Since a line length of the circuit is too long to be
ignored relative to the wavelength, the reflection from the active
element may produce a standing wave in the line causing change in
the load impedance depending upon the frequency to easily occur;
and
[0005] (2) since a reverse-direction transfer coefficient cannot be
reduced due to an existing inner capacitance of the active element,
a back-flow of signals may extremely increase to cause an unstable
phenomenon such as oscillation and runaway of the circuit or a
large variation in a frequency characteristics of the circuit.
[0006] In order to solve such the problems, it is very effective to
insert a non-reciprocal circuit element such as an isolator between
active elements so as to reduce the standing wave.
[0007] A monolithic millimeter-wave integrated circuit has been
demanded as a future semiconductor integrated circuit operating at
a millimeter-wave range. However, because a current semiconductor
element for a millimeter-wave range has a low manufacturing yield,
mass production is quite difficult for a monolithic millimeter-wave
integrated circuit. Therefore, in order to solve the yield problem,
it is most effective to fabricate a millimeter-wave hybrid
integrated circuit with a dielectric board. For a stable operation
of such hybrid integrated circuit, a millimeter-wave isolator acts
as an extremely important circuit element.
[0008] The operation of the millimeter-wave isolator requires a
strong magnetic field. Namely, a typical circulator used at a
microwave band or a higher-wave band called as a distributed
element circulator consists of a TM.sub.110 resonator with a
magnetized ferrite body. A magnetic field to be applied to the
ferrite body increases with the increase in frequency, and thus in
the millimeter-wave band, a strong magnetic field of 5000 Oe or
more is required. A conventional millimeter-wave isolator obtains
such a strong magnetic field from an externally mounted magnetic
circuit with an extremely large size. Therefore, it is hardly
possible to mount the conventional millimeter-wave isolator and the
magnetic circuit onto a millimeter-wave hybrid integrated
circuit.
SUMMARY OF THE INVENTION
[0009] It is therefore an object of the present invention to
provide a non-reciprocal circuit element which can be easily
mounted onto a millimeter-wave hybrid integrated circuit board, and
a millimeter-wave hybrid integrated circuit board with the
non-reciprocal circuit element.
[0010] The present invention is intended (1) to mount a
non-reciprocal circuit element such as an isolator on a
millimeter-wave hybrid integrated circuit board so as to eliminate
a wave reflected into the board, thereby stabilizing the circuit
operation, and (2) to form a pattern, on the millimeter-wave hybrid
integrated circuit board, for providing a non-reciprocal circuit
element only by mounting a spontaneously magnetized ferrite body
thereon as well as done in an ordinary component mounting
process.
[0011] According to the present invention, a non-reciprocal circuit
element includes a microstrip TM.sub.n10 resonator (n is a positive
integer) with a metal disk and branches projecting from the metal
disk in a trigonally symmetric structure, and a ferrite magnetic
body spontaneously magnetized and coaxially disposed on the
microstrip TM.sub.n10 resonator. The metal disk and the branches
are formed on a non-magnetic dielectric board having a ground
conductor on its bottom face. The ferrite magnetic body is arranged
so that a position of an electric field node matches to one of the
branches. Thus, the non-reciprocal circuit element can be easily
mounted onto a millimeter-wave hybrid integrated circuit board.
[0012] In other words, according to the present invention,
trigonally symmetric branches are provided between lines connecting
integrated circuits on a millimeter-wave hybrid integrated circuit
board that is constituted by a non-magnetic dielectric board and
provided with a ground conductor on its back surface to form a
TM.sub.n10 resonator (n is a positive integer), and a magnetic body
is disposed thereon to form a circulator. Additionally, a
spontaneously magnetized ferrite magnetic body is used as the
magnetic body eliminating the need for an external magnetic
circuit. The ferrite magnetic body is magnetized and dimensioned
such that a position of an electric field node matches to one of
the branches (a third terminal not connected to the integrated
circuit). If this third terminal is terminated by a matching
resistor, an isolator is formed.
[0013] If a reflected wave between integrated circuits is absorbed
by such a non-reciprocal circuit element, load impedance on a
signal-transmitting side becomes constant regardless of input
impedance on a signal-receiving side. Hence, it is possible to
prevent problems such as oscillation and runaway of a power
amplifier that are caused by the reflected wave in the circuit.
Particularly in case of a millimeter wave band amplifier, since an
increase in reverse-direction transfer constant of a transistor due
to inner capacitance of the element cannot be ignored, it is quite
important to make a signal to be directional in order to operate a
circuit with stability.
[0014] Preferably the ferrite magnetic body has a shape of a disk
or a cylinder.
[0015] It is preferred that the TM.sub.n10 resonator is a
TM.sub.m10 resonator, where m is a positive integer of 2 or more.
In this case, it is preferable to partially remove a portion of the
metal disk around a central axis or a portion of the ferrite
magnetic body and metal disk around the central axis. This
arrangement makes it possible to reduce TM.sub.010 mode, which is a
resonance frequency of the TM.sub.010 resonator, appearing in a
resonance frequency band of the TM.sub.m10 resonator.
[0016] As a modification, it is preferable to metallize an inner
wall of a hole formed in the ferrite magnetic body by removing a
portion around a central axis. Thus, the TM.sub.010 mode can be
suppressed more effectively.
[0017] It is also preferable to metallize at least the top and
bottom faces of the ferrite magnetic body. Hence, it is possible to
increase a magnetic flux appearing in the ferrite magnetic
body.
[0018] It is also preferred that the TM.sub.n10 resonator is a
TM.sub.110 resonator, and that a Faraday rotator with a ferrite
cylinder that has a metallized free end face and a propagation
length of one wavelength. As for a modification in this case,
preferably a non-magnetic dielectric body is coupled to the ferrite
cylinder.
[0019] It is preferred that a dielectric constant of the
non-magnetic dielectric body is selected such that the ferrite
cylinder and the non-magnetic dielectric body are equal to each
other in characteristic impedance. This arrangement makes it
possible to suppress reflection on a coupling surface between the
ferrite cylinder and the non-magnetic dielectric body.
[0020] Preferably, 1/4 wavelength impedance matching elements are
connected to the branches, respectively. This arrangement makes it
possible to widen an operational frequency band.
[0021] It is preferred that one terminal is connected to a matching
resistor and other two terminals are formed as input and output
terminals.
[0022] It is also preferred that the dielectric board is a
millimeter-wave hybrid integrated circuit board.
[0023] According to the present invention, furthermore, a
millimeter-wave hybrid integrated circuit board has at least one
non-reciprocal circuit element mentioned above.
[0024] Further objects and advantages of the present invention will
be apparent from the following description of the preferred
embodiments of the invention as illustrated in the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 shows a partially broken perspective view
illustrating a conventional distributed element circulator with a
typical configuration;
[0026] FIG. 2 shows an electric field distribution diagram of a
dielectric TM.sub.110 mode resonator in a preferred embodiment
according to the present invention;
[0027] FIG. 3 shows a diagram illustrating a magnetic
fieldfrequency characteristic of a gyro permeability;
[0028] FIGS. 4a and 4b show a perspective view schematically
illustrating the configuration of a circulator using the dielectric
TM.sub.110 mode resonator, and an electric field distribution
diagram of the circulator;
[0029] FIG. 5 shows a perspective view schematically illustrating
the configuration of a circulator using a higher-order mode
resonator in another embodiment according to the present
invention;
[0030] FIGS. 6a and 6b show perspective views illustrating the
configuration of the circulator shown in FIG. 5 as well as its
electromagnetic field distribution, and an electric field
distribution diagram;
[0031] FIG. 7 shows an electric field distribution diagram of
TM.sub.010 mode resonator;
[0032] FIG. 8 shows a perspective view schematically illustrating
the configuration of a circulator using a higher-order mode
resonator in a further embodiment according to the present
invention;
[0033] FIG. 9 shows a perspective view schematically illustrating
the configuration of a circulator using a higher-order mode
resonator in a still further embodiment according to the present
invention;
[0034] FIG. 10 shows a perspective view schematically illustrating
the configuration of a circulator using a Faraday rotator as well
as its electromagnetic field distribution in a further embodiment
according to the present invention;
[0035] FIG. 11 shows a perspective view schematically illustrating
the configuration of a circulator using a Faraday rotator as well
as its electromagnetic field distribution in a still further
embodiment according to the present invention;
[0036] FIG. 12 shows a perspective view schematically illustrating
the configuration of a circulator using a Faraday rotator as well
as its electromagnetic field distribution in a further embodiment
according to the present invention; and
[0037] FIG. 13 shows a perspective view schematically illustrating
the configuration of a millimeter-wave hybrid integrated circuit
board on which a non-reciprocal circuit element according to the
present invention is mounted.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0038] A distributed element circulator utilizes phenomena in which
a propagating speed of a radio wave in a magnetized ferrite depends
upon a rotational direction of a RF magnetic field applied to the
ferrite. FIG. 1 illustrates is a partially cutaway perspective view
showing a conventional typical distributed-element circulator.
[0039] In the figure, reference numeral 10 denotes a dielectric
substrate or board, 11 a ground conductor formed on the bottom face
of the dielectric board, 12 a ferrite disk inserted into a cut off
portion of the dielectric board 10, 13 a metal disk formed on the
top face of the ferrite disk 12, 14a, 14b and 14c terminals
extending in a radial direction from the metal disk 13 in a
trigonally symmetric structure, and 15 an exciting permanent magnet
provided on the metal disk 13, respectively.
[0040] As will be noted, in the conventional typical distributed
element circulator, the ferrite disk 12 is inserted between the
ground electrode 11 and the metal disk 13 and the terminals of
triple symmetry 14a, 14b and 14c are formed at the metal disk 13 to
form a TM.sub.110 resonator.
[0041] Whereas according to the present invention, a dielectric
TM.sub.n10 (n is a positive integer) mode resonator is used.
Hereinafter, embodiments of the present invention will be described
in detail.
[0042] FIG. 2 illustrates an electric field distribution of a
dielectric TM.sub.110 mode resonator in a preferred embodiment
according to the present invention, FIG. 3 illustrates a magnetic
field versus frequency characteristic of gyro permeability, and
FIGS. 4a and 4b schematically illustrate the configuration of a
circulator using the dielectric TM.sub.110 mode resonator and an
electric field distribution in the circulator.
[0043] In these figures, reference numeral 20 denotes a dielectric
board or substrate composed of a millimeter-wave hybrid integrated
circuit board, 21 a ground conductor formed on the bottom face of
the dielectric board 20, 23 a metal disk formed on the top face of
the dielectric board 20, 24a, 24b and 24c terminals formed on the
top face of the dielectric board 20 and extending in a radial
direction from the metal disk 23 in a tigonally symmetric
structure, and 25 a ferrite disk provided on the metal disk 23,
respectively.
[0044] A radius of the metal disk 23 of the dielectric TM.sub.110
mode resonator shown in FIG. 2 is given from the following equation
(1);
J.sub.0(ka)-(J.sub.1(ka)/ka)=0
k=2.pi.F{square root}{square root over (.di-elect cons.)}/c (1)
[0045] where J.sub.n is an n-order Bessel function, k is the number
of waves, .di-elect cons. is a dielectric constant of the board, F
is a frequency (Hz), c is a speed of light (mm/sec) and a is a
radius (mm) of the TM.sub.n10 mode resonator.
[0046] In case that a board with a dielectric constant of .di-elect
cons.=2 is used for the dielectric TM.sub.110 mode resonator
operating at F=60 GHz, a radius of the metal disk is calculated as
a=1.20 mm.
[0047] If a signal with a frequency satisfying the above condition
is applied to the terminal 24a of the resonator, because a speed of
a signal propagating on the metal disk 23 is equal in clockwise and
counterclockwise directions, an electric field 26 and a magnetic
field 27 on the metal disk 23 are distributed as shown in FIG. 2.
Since an electric field node 28 on the resonator is orthogonal to
the terminal 24a, the remaining terminals 24b and 24c output
signals with the same amplitude. Such an isotropic output
characteristic is achieved because an effective transmission-path
length of a signal propagating counterclockwise and also of a
signal propagating clockwise on the metal disk 23 is equal to an
integral multiple of a half wavelength. Even if a signal is applied
from the terminal 24b or 24c, the isotropic output will be obtained
from the remaining two terminals 24a and 24c or the two terminals
24a and 24b, respectively.
[0048] A circulator is formed by mounting, on the metal disk 23 of
the resonator, the ferrite disk 25 magnetized in the same direction
as the central axis of the metal disk 23. The RF magnetic field 27
on the metal disk 23 is orthogonal to the magnetization direction
of the ferrite disk 22 as shown in FIG. 2. If the RF magnetic field
and the DC magnetic field are orthogonal to each other, the
magnetic material body will provide a gyro permeability shown in
FIG. 3 and thus signals propagating clockwise and counterclockwise
differ in effective transmission path length due to the difference
in permeability (.mu..sub.+ and .mu..sub.-) that depends upon the
sense direction of the RF magnetic field. Assuming that adjustment
is made such that the difference between a clockwise path length
and a counterclockwise path length is equal to a half wavelength
from the terminal 24a to the terminal 24b. In this case, since the
electromagnetic field distribution becomes such that, as shown in
FIG. 4a, the electric field node 28 matches to the terminal 24b, an
output cannot be obtained from the terminal 24b and all signals
appear at the terminal 24c. In such a three-terminals circulator,
the terminal 24a is referred to as an input terminal, the terminal
24c as an output terminal, and the terminal 24b as an isolation
terminal.
[0049] When a signal is applied to the terminal 24b, the
relationship of the transmission path difference rotates
counterclockwise by 120.sup..OMEGA., and therefore the terminal 24b
serves as an input terminal, the terminal 24c an output terminal,
and the terminal 24a an isolation terminal. Since when an input
terminal is changed, the relationship with an output terminal is
accordingly changed in a circulating manner, such element is called
as a circulator and such conditions for providing a transmission
path difference is called as circulator conditions.
[0050] As will be understood from the above description, the
circulator constituted by the TM.sub.110 mode resonator is a
non-reciprocal circuit element with an electric field node rotated
by 30.sup..OMEGA. according to a gyro permeability of a magnetic
material body as shown in FIG. 4b.
[0051] It should be noted that such a resonator-type circulator is
not limited to the TM.sub.110 resonator but any TM.sub.n10
resonator (n: a positive integer) can be used in a distributed
element circulator if the TM.sub.n10 resonator is constructed so
that its electric field node matches to one of its terminals.
[0052] Because a gyro permeability appears due to ferromagnetic
resonance, both permeabilities due to rotational directions of the
RF magnetic field approach to one with an increase in a frequency
as shown in FIG. 3. Thus, the difference in the permeabilities is
reduced and therefore the circulator conditions cannot be
satisfied. For this reason, in a frequency band such as a
millimeter-wave band, it is necessary to increase the resonance
frequency by applying a strong DC magnetic field and to increase
the difference between permeabilities due to rotational
directions.
[0053] If a millimeter-wave circuit circulator has a typical
magnetic circuit for externally applying magnetic field, because of
the large volume magnetic circuit, the size of the circulator
becomes too large to fit into a board. A spontaneously magnetized
ferrite such as a barium ferrite may be used to avoid increase in
size of the magnetic circuit, as partially put into practice in the
microwave band (W.W. Sienkanowicz et al., G-MTT Sym. Digest, p.79,
May 1967). However, if the ferrite resonator is used, it is
necessary, as shown in FIG. 1, to sandwich the ferrite disk 12
between the metal disk 13 and the ground conductor 11 causing the
mounting of the circulator on the board to become extremely
inconvenient.
[0054] Thus, in this embodiment, a TM.sub.110 resonator is
constructed by disposing a metal disk and trigonally symmetric
terminals on the top face of a millimeter-wave hybrid integrated
circuit board which is a dielectric board with a ground conductor
covering its bottom face, and a ferrite body is disposed only on
the upper face of the metal disk of the TM.sub.110 resonator to
form a circulator.
[0055] Therefore, the circulator can be constructed only by
disposing the spontaneously magnetized ferrite magnetic body on the
millimeter-wave hybrid integrated circuit board, resulting the
mounting of the circulator to be extremely easily performed.
[0056] FIG. 5 schematically illustrates the configuration of a
circulator using a higher-order mode resonator in another
embodiment according to the present invention, FIGS. 6a and 6b
illustrate the configuration of the circulator and its
electromagnetic field distribution, and FIG. 7 illustrates an
electric field distribution in a TM.sub.010 mode resonator.
[0057] In the above-mentioned circulator shown in FIGS. 2, 4a and
4b, in which the gyro magnetic body is mounted on the dielectric
TM.sub.110 resonator to rotate the electric field node, no rotation
of the electric filed node will occur at the dielectric TM.sub.110
resonator itself because this resonator is made of a non-magnetic
dielectric material. Thus, it is necessary that the mounted gyro
magnetic body rotates the electric field node by an angle
approximately twice an electric field node rotational angle
required for a typical circulator. The rotational angle of the
electric field node increases in proportion to a saturation
magnetization of the ferrite. However, since a barium ferrite has a
small saturation magnetization, the assembling of a barium ferrite
body with a TM.sub.110 resonator will not provide a circulator with
a sufficient rotational angle. For this reason, in this embodiment,
instead of the conventional TM.sub.110 resonator circulator, a
higher-order mode resonator such as a TM.sub.210 resonator is used
to form a circulator.
[0058] In FIGS. 5, 6a and 6b, reference numeral 50 denotes a
dielectric board or substrate composed of a millimeter-wave hybrid
integrated circuit board, 51 a ground conductor formed on the
bottom face of the dielectric board 50, 53 a metal disk provided
with a through hole 53a at its center and formed on the top face of
the dielectric board 50, 54a, 54b and 54c terminals formed on the
top face of the dielectric board 50 and extending in a radial
direction from the metal disk 53 in a tigonally symmetric
structure, 55 a ferrite disk provided with a through hole 55a at
its center and formed on the metal disk 53 so as to be magnetized
in the same direction as the central axis of the metal disk 53, 56
an electric field, 57 a magnetic field, 58 an electric field node,
and 59 DC magnetization, respectively.
[0059] In this embodiment, a TM.sub.210 resonator is constructed by
disposing a metal disk and trigonally symmetric terminals on the
top face of a millimeter-wave hybrid integrated circuit board which
is a dielectric board with a ground conductor covering its bottom
face, and a ferrite body is disposed only on the upper face of the
metal disk of the TM.sub.210 resonator to form a circulator.
[0060] As aforementioned, a circulator can be formed by using a
TM.sub.n10 resonator if its electric field node matches to the
isolation terminal. In case of using a TM.sub.210 mode resonator,
the circulator will be formed by matching the electric field node
to a rotational angle of 15.sup..OMEGA.. Namely, according to this
embodiment, by using a higher-order TM.sub.n10 mode resonator, a
circulator can be provided even if a magnetic body such as a barium
ferrite body having a small difference in permeabilities due to
magnetic field rotational directions is used and it results a small
rotational angle of the electric field node.
[0061] Although the higher-order mode resonator is larger in size
than a fundamental mode resonator, as long as used for a signal
with a short wavelength such as a millimeter wave, it is possible
to provide a circulator that sufficiently matches with a circuit
element in size.
[0062] In many higher-order mode resonators, a resonance frequency
of the TM.sub.010 mode appears at a lower frequency than that of
the corresponding higher-order mode, and the TM.sub.010 mode may
coexist with the higher-order mode. As shown in FIG. 7, since the
TM.sub.010 resonance mode does not have an electric field node, a
circulator cannot be formed and the operation of the circulator is
interfered by the coexistence of an electric field 76 concentrating
at a central part.
[0063] Therefore, in this embodiment, the through hole 53a is
formed to remove the central part of the metal disk 53 so that an
electric field does not appear at a central axis. Thus, the
resonance frequency of the TM.sub.010 mode in the circulator is
shifted to a higher frequency than the TM.sub.n10 mode resonance
frequency.
[0064] In this embodiment, a ferrite magnetic body is disposed only
on the upper side of the resonator, unlike the conventional
circulator having ferrite bodies with a non-reciprocal transmitting
property on top and bottom faces of the resonator. Thus, in
designing the circulator, it is difficult to analytically determine
the conditions of the circulator. Therefore, in this embodiment, a
design method based on sequential approximation as follows is
adopted.
[0065] First, a disk diameter of a TM.sub.210 mode resonator of the
dielectric board is calculated. Then, a magnetized ferrite disk
with a thickness is mounted thereon to form a circulator. The
thickness of the ferrite disk is determined by considering a fact
that a transmission path difference varies substantially in
proportion to the thickness of the ferrite disk.
[0066] Assuming that a circulator is mounted onto a millimeter-wave
hybrid integrated circuit board including a plurality of
semiconductor elements mounted on a dielectric board with a
dielectric constant of .di-elect cons.=2. A radius a (mm) of a
resonating disk with the TM.sub.210 mode is calculated by equation
(2);
J.sub.1(ka)-(2J.sub.2(ka)/ka)=0
k=2.pi.F {square root}{square root over (.di-elect cons.)}/c
(2)
[0067] Minimum ka satisfying this equation is 3.05. Therefore, in
the TM.sub.210 mode resonator operating at 60 GHz on the board
having the dielectric constant of .di-elect cons.=2, the radius a
of the metal disk 53 is determined to a=1.98 mm.
[0068] On the metal disk 53, the ferrite disk 55 made of a barium
ferrite and equal to the metal disk 53 in diameter, with a
thickness satisfying the circulator conditions is disposed. As
shown in FIG. 6a, in the TM.sub.210 mode, the RF magnetic field 57
hardly exists at the center of the ferrite disk 55. Thus, the
through hole 55a is formed at the center of the ferrite disk 55 in
the same manner as the metal disk 53 to prevent the occurrence of
the TM.sub.010 mode.
[0069] In this embodiment, a top face 55b and the bottom face of
the ferrite disk 55 are metallized by evaporating or plating a
metal. This metallization aims to increase a magnetic flux
appearing inside of the ferrite disk but is not always necessary to
form the circulator of the present invention.
[0070] As will be apparent from FIG. 3, gyro magnetization is
observed in regions lower and higher than the resonance condition
or the resonance magnetic field. As for a circulator such as a
millimeter-wave circulator requiring a high DC magnetic field, gyro
magnetization appearing in the below resonance region is used.
Assuming that a gyro permeability is roughly estimated based on a
saturation magnetization of 3500 G of the barium ferrite and an
internal magnetic field of 5000 Oe, the thickness of the ferrite
disk 55 in the circulator operating at 60 GHz is determined to 0.5
mm.
[0071] Other configurations, advantages and modifications of this
embodiment are the similar to those of the embodiment shown in FIG.
2.
[0072] FIG. 8 schematically illustrates the configuration of a
circulator using a higher-order mode resonator in a further
embodiment according to the present invention.
[0073] In the figure, reference numeral 80 denotes a dielectric
board or substrate composed of a millimeter-wave hybrid integrated
circuit board, 81 a ground conductor formed on the bottom face of
the dielectric board 80, 83 a metal disk provided with a through
hole 83a at its center and formed on the top face of the dielectric
board 80, 84a, 84b and 84c terminals formed on the top face of the
dielectric board 80 and extending in a radial direction from the
metal disk 83 in a tigonally symmetric structure, and 85 a ferrite
disk provided with a through hole 85a at its center and formed on
the metal disk 83 so as to be magnetized in the same direction as
the central axis of the metal disk 83, respectively.
[0074] In this embodiment as well as in the embodiment of FIG. 5, a
TM.sub.210 resonator is constructed by disposing a metal disk and
trigonally symmetric terminals on the top face of a millimeter-wave
hybrid integrated circuit board which is a dielectric board with a
ground conductor covering its bottom face, and a ferrite body is
disposed only on the upper face of the metal disk of the TM.sub.210
resonator to form a circulator. Although only the top and bottom
faces of the ferrite disk are metallized in the embodiment of FIG.
5, the inner wall of the through hole 85a in the ferrite disk 85 is
additionally metallized by evaporating or plating metal in this
embodiment. With this arrangement, it is possible to suppress a
TM.sub.010 mode more effectively.
[0075] Other configurations, advantages and modifications of this
embodiment are the similar to those of the embodiment shown in FIG.
5.
[0076] FIG. 9 schematically illustrates the configuration of a
circulator using a higher-order mode resonator in a still further
embodiment according to the present invention.
[0077] In the figure, reference numeral 90 denotes a dielectric
board or substrate composed of a millimeter-wave hybrid integrated
circuit board, 91 a ground conductor formed on the bottom face of
the dielectric board 90, 93 a metal disk provided with a through
hole 93a at its center and formed on the top face of the dielectric
board 90, 94a, 94b and 94c terminals formed on the top face of the
dielectric board 90 and extending in a radial direction from the
metal disk 93 in a tigonally symmetric structure, and 95 a ferrite
disk provided with a through hole 95a at its center and formed on
the metal disk 93 so as to be magnetized in the same direction as
the central axis of the metal disk 93, respectively.
[0078] Also in this embodiment as well as in the embodiment of FIG.
5, a TM.sub.210 resonator is constructed by disposing a metal disk
and trigonally symmetric terminals on the top face of a
millimeter-wave hybrid integrated circuit board which is a
dielectric board with a ground conductor covering its bottom face,
and a ferrite body is disposed only on the upper face of the metal
disk of the TM.sub.210 resonator to form a circulator.
[0079] Further, in this embodiment, 1/4 wavelength impedance
transformers 92a, 92b and 92c are respectively inserted into the
terminals (branches) 94a, 94b and 94c so as to widen an operational
frequency band of the circulator. This arrangement is provided to
solve a problem of a narrow operational frequency band caused by
the higher-order mode circulator in which an electric field node
shifts largely depending upon the frequency.
[0080] In the present embodiment as well as in the embodiment of
FIG. 5, the top and bottom faces of the ferrite disk may be
metallized. Further, as in the embodiment of FIG. 8, the inner wall
of the through hole in the ferrite disk may additionally be
metallized.
[0081] Other configurations, advantages and modifications of this
embodiment are the similar to those of the embodiments shown in
FIGS. 5 and 8. It is self-evident that the mode number m is not
limited to 2, but m.gtoreq.3. Namely, a circulator can be obtained
equivalent to the circulator in this embodiment as long as the
circulator conditions of that an electric field node conforms to
one of the terminals is satisfied even under a whispering gallery
mode of m.gtoreq.3.
[0082] FIG. 10 schematically illustrates the configuration of a
circulator using Faraday rotator as well as its electromagnetic
field distribution in a further embodiment according to the present
invention.
[0083] In the figure, reference numeral 100 denotes a dielectric
board or substrate composed of a millimeter-wave hybrid integrated
circuit board, 101 a ground conductor formed on the bottom face of
the dielectric board 100, 103 a metal disk formed on the top face
of the dielectric board 100, 104a, 104b and 104c terminals formed
on the top face of the dielectric board 100 and extending in a
radial direction from the metal disk 103 in a tigonally symmetric
structure, 105 a ferrite cylinder formed on the metal disk 103 so
as to be magnetized in the same direction as the central axis of
the metal disk 103, 107 a short-circuit plate constituted by a
metal plate formed on the top end face of the ferrite cylinder 105,
108a an electric field node of a dielectric resonator, 108b an
electric field node of a Faraday resonator, 108 a combined electric
field node which is a combination of the above-mentioned nodes, and
109 DC magnetization, respectively.
[0084] In this embodiment, a TM.sub.n10 resonator is constructed by
disposing a metal disk and trigonally symmetric terminals on the
top face of a millimeter-wave hybrid integrated circuit board which
is a dielectric board with a ground conductor covering its bottom
face, and a ferrite cylinder or a Faraday rotator is disposed only
on the upper face of the metal disk of the TM.sub.n10 resonator to
form a circulator.
[0085] A circulator constituted by combining transmitting
properties of resonators disposed on both the top and bottom faces
of a dielectric board can be realized, as well as the TM.sub.n10
mode resonator using the ferrite body, from a dielectric TM.sub.n10
mode resonator and a Faraday rotator with a electric field node
rotation satisfying the circulator conditions mounted on the
dielectric TM.sub.n10 mode resonator as in this embodiment.
[0086] Now, the operating principles of the circulator using the
Faraday rotator will be described based on a Faraday effect.
[0087] If a RF signal with a magnetic field orthogonal to a DC
magnetization axis is propagated through a ferrite cylinder which
is DC magnetized in a central axis direction, the direction (plane
of polarization) of the RF electromagnetic field will rotate
together with the signal propagation. This is because the
propagation of the RF magnetic field differs between rotational
directions. Such rotation of the polarization plane is called as a
Faraday effect. In case that the applied magnetic field is lower
than a resonance magnetic field, the polarization plane rotates in
a negative direction (clockwise direction) relative to the
propagating direction.
[0088] As shown in FIG. 10, in this embodiment, one end of the
ferrite cylinder 105 is short-circuited by the metal plate 107 and
this ferrite cylinder 105 is disposed on the dielectric resonator.
If the ferrite cylinder 105 is spontaneously magnetized in its
central axis direction, an electromagnetic wave applied from the
dielectric resonator to the ferrite cylinder 105 rotates its
polarization plane while being propagated by the Faraday effect.
The electric field node 108b in the ferrite cylinder 105 also
rotates in the same manner. Here, a rotational angle of the
polarization plane or the electric field node is represented by
.theta.. The electromagnetic wave reaching the top end face of the
ferrite cylinder 105 is reflected on the metal plate 107 and
reverses its propagating direction. This reflected wave further
rotates the electric field node 108b due to the Faraday effect, and
the rotational angle of the electric field node becomes 2.theta. at
the top face of the dielectric resonator. The electric field node
108 on a resonator is determined by combining the electric field
node 108a of the dielectric resonator mainly constituted by the
dielectric board and the electric field node 108b rotated in the
ferrite cylinder 105. Thus, when the combined electric field node
108 matches to one of the terminals other than the input terminal,
the resonator can act as a circulator using the matched terminal as
an isolation terminal.
[0089] In such the circulator, the rotational angle of the electric
field node is determined in accordance with an axial length of the
ferrite cylinder 105. Therefore, even if the resonator on the board
section has a TM.sub.n10 mode, it is possible to obtain a necessary
rotation of the electric field node contributing to downsizing of
the circulator.
[0090] In case of a TM.sub.110 mode Faraday rotating circulator
operating at 60 GHz formed on a dielectric board with a dielectric
constant of .di-elect cons.=2, a diameter of the metal disk of the
TM.sub.110 mode resonator is determined to D=2.40 mm according to
equation (1). It is assumed that the barium ferrite cylinder is
equal to the metal disk in diameter and that an inner line length
of the cylinder is one wavelength. Since an internal DC magnetic
field is lower than a resonance magnetic field in this embodiment,
an average relative permeability that is an average value of
relative gyro permeabilities for positive and negative rotating
magnetic fields becomes 0.8. A propagating wavelength in the
cylinder is reduced to a geometric average value of the dielectric
constant and the average relative permeability. If barium ferrite
has a dielectric constant of .di-elect cons.=16, a wavelength
reduction ratio becomes 1/3.51 and a length of the ferrite cylinder
becomes 1.40 mm.
[0091] Other configurations, advantages and modifications of this
embodiment are the same as those of the embodiments shown in FIGS.
5, 8 and 9.
[0092] FIG. 11 schematically illustrates the configuration of a
circulator using Faraday rotator as well as its electromagnetic
field distribution in a still further embodiment according to the
present invention.
[0093] In the figure, reference numeral 110 denotes a dielectric
board or substrate composed of a millimeter-wave hybrid integrated
circuit board, 111 a ground conductor formed on the bottom face of
the dielectric board 110, 113 a metal disk formed on the top face
of the dielectric board 110, 114a, 114b and 114c terminals formed
on the top face of the dielectric board 110 and extending in a
radial direction from the metal disk 113 in a tigonally symmetric
structure, 115 a ferrite cylinder formed on the metal disk 113 so
as to be magnetized in the same direction as the central axis of
the metal disk 113, 116 a dielectric cylinder attached to the top
face of the ferrite cylinder 115, 117 a short-circuit plate
constituted by a metal plate formed on the top end face of the
dielectric cylinder 116, 118a an electric field node of a
dielectric resonator, 118b an electric field node of a Faraday
resonator, and 118 a combined electric field node which is a
combination of the above-mentioned nodes, respectively.
[0094] In this embodiment, a TM.sub.n10 resonator is constructed by
disposing a metal disk and trigonally symmetric terminals on the
top face of a millimeter-wave hybrid integrated circuit board which
is a dielectric board with a ground conductor covering its bottom
face, and a ferrite cylinder or a Faraday rotator is disposed only
on the upper face of the metal disk of the TM.sub.n10 resonator to
form a circulator. Particularly, in this embodiment, the dielectric
cylinder 116, one end of which is short-circuited by the metal
plate 117, is coupled to the ferrite cylinder 115.
[0095] If the dielectric resonator is constituted by a non-magnetic
dielectric board, the ferrite cylinder will act as an independent
resonator and needs to produce resonance in phase with the
dielectric resonator formed at the dielectric board. Therefore, in
this case, an inner line length of the ferrite cylinder is required
to be equal to a wavelength. However, it is difficult to
simultaneously satisfy both requirements for a rotational angle of
the electric field node and for the line length. Thus, in this
embodiment, the dielectric cylinder 116 is connected to the ferrite
cylinder 115 so as to provide a function of adjusting only a phase
amount regardless of rotation in the electric field node.
[0096] In order to prevent reflection on a coupling face to the
ferrite body, it is preferable that a dielectric constant of the
dielectric cylinder 116 for adjusting a phase be set to a value
whereby the ferrite cylinder 115 and the dielectric cylinder 116
are equal to each other in characteristic impedance. A relative
dielectric constant .di-elect cons..sub.d of the dielectric
cylinder 116 is calculated by equation (3), so that matching can be
achieved on the coupling face;
{square root}{square root over (1/.di-elect cons..sub.d)}={square
root}{square root over (.di-elect cons..sub.f/.di-elect
cons..sub.f)} (3)
[0097] where .di-elect cons..sub.d is a relative dielectric
constant of the dielectric cylinder for adjusting a phase,
.mu..sub.f is an average relative permeability of the ferrite
cylinder, and .di-elect cons..sub.f is a relative dielectric
constant of the ferrite cylinder.
[0098] A thickness of the dielectric cylinder 116 may be determined
to any value because a necessary thickness of the dielectric body
for constituting a circulator differs depending upon positive and
negative gyro permeabilities. However, the thickness of the
dielectric cylinder 116 will be normally set at about 0.1 to 0.2
wavelength so as to not exceed a range of a phase adjustment
element.
[0099] In such the circulator, the rotational angle of the electric
field node is determined in accordance with an axial length of the
ferrite cylinder 115. Therefore, even if the resonator on the board
section has a TM.sub.n10 mode, it is possible to obtain a necessary
rotation of the electric field node contributing to downsizing of
the circulator.
[0100] Other configurations, advantages and modifications of this
embodiment are the same as those of the embodiments shown in FIGS.
5, 8, 9 and 10.
[0101] FIG. 12 schematically illustrates the configuration of a
circulator using Faraday rotator as well as its electromagnetic
field distribution in a further embodiment according to the present
invention.
[0102] In the figure, reference numeral 120 denotes a dielectric
board or substrate composed of a millimeter-wave hybrid integrated
circuit board, 121 a ground conductor formed on the bottom face of
the dielectric board 120, 123 a metal disk formed on the top face
of the dielectric board 120, 124a, 124b and 124c terminals formed
on the top face of the dielectric board 120 and extending in a
radial direction from the metal disk 123 in a tigonally symmetric
structure, 125 a ferrite cylinder formed on the metal disk 123 so
as to be magnetized in the same direction as the central axis of
the metal disk 123, 126 a dielectric cylinder attached to the top
face of the ferrite cylinder 125, and 127 a short-circuit plate
constituted by a metal plate formed on the top end face of the
dielectric cylinder 126, respectively.
[0103] In this embodiment as well as the embodiment of FIG. 11, a
TM.sub.n10 resonator is constructed by disposing a metal disk and
trigonally symmetric terminals on the top face of a millimeter-wave
hybrid integrated circuit board which is a dielectric board with a
ground conductor covering its bottom face, and a ferrite cylinder
or a Faraday rotator is disposed only on the upper face of the
metal disk of the TM.sub.n10 resonator to form a circulator. Also,
the dielectric cylinder 126, one end of which is short-circuited by
the metal plate 127, is coupled to the ferrite cylinder 125.
[0104] Furthermore, in this embodiment, {fraction (1/4)} wavelength
impedance transformers 122a, 122b and 122c are respectively
inserted into the terminals (branches) 124a, 124b and 124c so as to
widen an operational frequency band of the circulator. This
arrangement is provided to solve a problem of a narrow operational
frequency band caused by the higher-order mode circulator in which
an electric field node shifts largely depending upon the
frequency.
[0105] Other configurations, advantages and modifications of this
embodiment are the same as those of the embodiments shown in FIGS.
5, 8, 9, 10 and 11.
[0106] FIG. 13 schematically illustrates the configuration of a
millimeter-wave hybrid integrated circuit board on which a
non-reciprocal circuit element of the present invention is
mounted.
[0107] In the figure, reference numeral 130 denotes a dielectric
board which is a millimeter-wave hybrid integrated circuit board
mounted in a package 131, 132 and 133 active elements such as
semiconductor integrated circuits mounted on the dielectric board
130, 134 and 135 circulators/isolators formed on the dielectric
board 130 with the similar configuration of the aforementioned
embodiments, and 136 and 137 matching resistances, respectively.
Although it is not shown in FIG. 13, a ground conductor is formed
on the bottom face of the dielectric board 130 to cover the whole
surface.
[0108] In the hybrid integrated circuit constructed by mounting a
plurality of the active elements 132 and 133 on the dielectric
board 130, trigonally symmetric branches are provided on a line for
connecting two circuits, and metal disks are formed on the
symmetric centers to make dielectric circular TM.sub.n10 resonators
(n is a positive integer). A spontaneously magnetized ferrite disk,
a spontaneously magnetized ferrite cylinder, or a cylinder with the
ferrite cylinder and a phase-adjusting dielectric cylinder coupled
to the ferrite cylinder is disposed on each of the metal disks to
constitute circulator. The branches which are not connected to the
circuits on the dielectric board 130 are terminated by the matching
resistances 136 and 137 to form isolators for removing interference
between circuits.
[0109] If the above-mentioned branches, matching resistances and
metal disks are formed in a manufacturing process for forming the
dielectric board 130, it is possible to readily form isolators,
which are key parts for operating the millimeter-wave integrated
circuit with stability on the millimeter-wave hybrid integrated
circuit board, only by mounting spontaneously magnetized barium
ferrite bodies on patterns for TM.sub.n10 resonators in a similar
process to a process of mounting the active elements 132 and 133.
Therefore, it is not necessary to connect the circulator by using a
connector and/or to mount element into the board as the
conventional technique, and mounting of circulators and/or
isolators can be executed in a production line as well as done in
an ordinary component mounting process. Consequently, it is
possible to greatly contribute to the stability and mass production
of the millimeter-wave integrated circuit.
[0110] As described above in detail, according to the present
invention, a non-reciprocal circuit element includes a microstrip
TM.sub.n10 resonator (n is a positive integer) with a metal disk
and branches projecting from the metal disk in a trigonally
symmetric structure, and a ferrite magnetic body spontaneously
magnetized and coaxially disposed on the microstrip TM.sub.n10
resonator. The metal disk and the branches are formed on a
non-magnetic dielectric board having a ground conductor on its
bottom face. The ferrite magnetic body is arranged so that a
position of an electric field node matches to one of the branches.
Thus, the non-reciprocal circuit element can be easily mounted onto
a millimeter-wave hybrid integrated circuit board.
[0111] If a reflected wave between integrated circuits is absorbed
by such a non-reciprocal circuit element, load impedance on a
signal-transmitting side becomes constant regardless of input
impedance on a signal-receiving side. Hence, it is possible to
prevent problems such as oscillation and runaway of a power
amplifier that are caused by the reflected wave in the circuit.
Particularly in case of a millimeter wave band amplifier, since an
increase in reverse-direction transfer constant of a transistor due
to inner capacitance of the element cannot be ignored, it is quite
important to make a signal to be directional in order to operate a
circuit with stability.
[0112] Many widely different embodiments of the present invention
may be constructed without departing from the spirit and scope of
the present invention. It should be understood that the present
invention is not limited to the specific embodiments described in
the specification, except as defined in the appended claims.
* * * * *