Wave transmission lines and networks – Coupling networks – Nonreciprocal gyromagnetic type
Reexamination Certificate
2002-10-22
2004-05-11
Lee, Benny (Department: 2817)
Wave transmission lines and networks
Coupling networks
Nonreciprocal gyromagnetic type
C333S001100
Reexamination Certificate
active
06734754
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a nonreciprocal circuit device and a communication apparatus including a nonreciprocal circuit device.
2. Description of the Related Art
An isolator disclosed in Japanese Unexamined Patent Application Publication No. 2001-136006 is known as a conventional isolator. As shown in
FIG. 12
, an isolator
200
includes an upper metal casing member
201
, a permanent magnet
202
, a center electrode assembly
203
, a multilayer substrate
204
, an external-connection terminal component
205
, and a lower metal casing member
207
. Reference symbol R indicates a resistance element. The center electrode assembly
203
and the multilayer substrate
204
are accommodated in the external-connection terminal component
205
, and on the upper surface of the structure, the resistance element R and the permanent magnet
202
are arranged. The permanent magnet
202
, the center electrode assembly
203
, the multilayer substrate
204
, the external-connection terminal component
205
, and the resistance element R are then accommodated in the upper metal casing member
201
and the lower metal casing member
207
, thereby defining a nonreciprocal circuit. In this case, to connect external-connection terminals
209
of the external-connection terminal components
205
to a mounting substrate, a groove
206
, which has substantially the same depth as the thickness of the bottom section
208
of the lower metal casing member
207
, is formed at the lower surface of the external-connection terminal component
205
.
Since the isolator
200
requires the external-connection terminal component
205
as an individual component for connecting the external-connection terminals
209
to a mounting substrate, the cost of the isolator
200
is increased.
Another isolator disclosed in Japanese Unexamined Patent Application Publication No. 5-304404 is also known. As shown in
FIG. 13
, an isolator
300
includes a metal casing
301
, a permanent magnet
307
, a multilayer substrate
303
having a center electrode assembly therein, and a ferrite element
305
. Side surfaces of the multilayer substrate
303
are provided with external-connection terminals
306
for connection with a mounting substrate. The isolator
300
is constructed such that the permanent magnet
307
and the ferrite element
305
are accommodated in the multilayer substrate
303
, and the resulting structure is inserted into the metal casing
301
. In this case, the lower portion
302
of the metal casing
301
fits into a groove
304
of the multilayer substrate
303
. Thus, the multilayer substrate
303
has a cavity structure.
An isolator disclosed in Japanese Unexamined Patent Application Publication No. 9-55607 is also known as having a structure similar to that of the isolator
300
.
For such an isolator
300
, it has been difficult to manufacture such a multilayer substrate
303
, which is obtained by firing and has a cavity structure with a large hole in the center thereof, with high accuracy at a low cost.
SUMMARY OF THE INVENTION
In order to overcome the problems described above, preferred embodiments of the present invention provide a nonreciprocal circuit device and a less-expensive communication apparatus with a reduced number of components.
According to a preferred embodiment of the present invention, a nonreciprocal circuit device includes
(a) a permanent magnet;
(b) a center electrode assembly that includes a ferrite element, to which a direct-current magnetic field is applied by the permanent magnet, and a plurality of center electrodes, arranged on a major surface of the ferrite element;
(c) a multilayer substrate that has a first major surface and a second major surface opposing the first major surface and that includes matching capacitor elements connected to corresponding ends of the center electrodes, in which the center electrode assembly is arranged on the first major surface and a plurality of external-connection terminal electrodes is provided at the second major surface; and
(d) a metal casing that encloses the permanent magnet, the center electrode assembly, and the multilayer substrate; and
(e) the metal casing is partially provided on the second major surface of the multilayer substrate, and at least one of the plurality of external-connection terminal electrodes protrudes from the second major surface by an amount measurement that is substantially equal to the thickness of the metal casing. In this case, preferably, the height of the protrusion of the external-connection terminal electrode from the second major surface is in the range of about 0.1 mm to about 0.2 mm.
Preferred embodiments of the present invention, therefore, can provide the terminals with sufficient flatness, and the user can directly solder the external-connection terminal electrodes of the multilayer substrate to a mounting substrate, which can eliminate an external-connection terminal component that has been conventionally required. In addition, this arrangement can eliminate the need for forming a large hole in the center of the multilayer substrate, so that the multilayer substrate can be fired in a plate state, thereby suppressing the deformation of the multilayer substrate and increasing the dimensional accuracy thereof. This further offers advantages in that the dimensional accuracy of the multilayer substrate is increased and the fabrication process of the multilayer substrate can be greatly simplified, which therefore can provide a high-performance and less-expensive nonreciprocal circuit device.
Preferably, the at least one external-connection terminal electrode that protrudes from the second major surface by an amount that is a substantially equal to the thickness of the metal casing fits into a notch provided in the metal casing. With this arrangement, the multilayer substrate and the metal casing can be easily positioned.
Preferably, the second major surface of the multilayer substrate has a ground electrode arranged to cover substantially the entire second major surface and the ground electrode is electrically connected to the metal casing. This arrangement allows for a sufficient contact area between the ground electrode and the metal casing, thus improving the electrical characteristic of the nonreciprocal circuit device.
The external-connection terminal electrodes that protrude from the second major surface by an amount that is substantially equal to the thickness of the metal casing may be only an input terminal electrode and an output terminal electrode. In this case, the ground terminal electrode is soldered to the mounting substrate via the metal casing. Since the area of the interface at which the metal casing and the mounting substrate are joined is large, this arrangement can improve the mounting strength of the nonreciprocal circuit device. Further, the majority of thermal stress and mechanical stress is applied to an interface at which the metal casing and the mounting substrate are joined, thereby alleviating the stress applied to the interface between the input and output terminal electrodes and the mounting substrate. This also can improve reliability in the connection of the input and output terminal electrodes.
A second preferred embodiment of the present invention provides a communication apparatus. The communication apparatus includes the nonreciprocal circuit device constructed according to the preferred embodiment described above. Thus, the communication apparatus offers the same advantages as those of the nonreciprocal circuit device according to other preferred embodiments of the present invention, thus allowing for a reduction in the manufacturing cost and an improvement in the electrical characteristic.
Other features, elements, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.
REFERENCES:
patent: 6462628 (2002-10-01), Kondo et al.
patent: 1 139 486 (2001
Saito Kenji
Yoneda Masayuki
Jones Stephen E.
Keating & Bennett LLP
Lee Benny
Murata Manufacturing Co. Ltd.
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