Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
2001-06-29
2004-01-13
Paladini, Albert W. (Department: 2827)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C174S261000
Reexamination Certificate
active
06677537
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a nonreciprocal circuit device such as an isolator and a circulator used at microwave bands, and relates to a mounting structure of the nonreciprocal circuit device and a communication apparatus having the nonreciprocal circuit device.
2. Description of the Related Art
Hitherto, a concentrated-constant-type isolator, for example, comprises a ferrite assembly having a plate-like ferrite with plural central conductors closely arranged thereto and intersecting with each other, a magnet accommodated in a case for applying a static magnetic field to the ferrite, and input-output terminals exposed or protruded outside the case.
FIGS. 13A
to
15
B show a method for pulling out the input-output terminals from the case of such a conventional isolator and a structure for mounting the isolator on a substrate of a communication apparatus or the like.
FIG. 13A
is a perspective view of the isolator;
FIG. 13B
is a perspective view showing a state that the isolator is mounted on a printed circuit board of a communication apparatus. In this example, the input-output terminals of the isolator are respectively arranged on the substantially bottom surface of the isolator and the isolator is surface-mounted by soldering the input-output terminals of the isolator to connecting pads on the printed circuit board. A module circuit board
3
forming a circuit module is surface-mounted on the printed circuit board
2
, and the circuit on the module circuit board
3
and the isolator are electrically connected together via an electrode pattern formed on the printed circuit board
2
.
FIG. 14A
is a side view of an isolator of another structure;
FIG. 14B
is a drawing showing a mounting structure thereof. In this example, input-output terminals are pulled out of intermediate portions of the part height of the isolator. As shown in
FIG. 14B
, when the bottom surface of the isolator body is a grounding conductor: the isolator body is fixed on an earth block (a common earth plate) with screws; the printed circuit board
2
having the same shaped-opening as the planar external shape of the isolator is arranged on the earth block; the isolator is fitted into the opening of the printed circuit board
2
; the input-output terminals of the isolator are soldered to connecting pads on the printed circuit board
2
.
FIG. 15A
is a side view of still another isolator;
FIG. 15B
is a drawing showing a mounting structure thereof. This example is basically of the same structure as that shown in
FIGS. 14A and 14B
; however, input-output terminals are pulled out of the top surface of the isolator. This mounting structure may be adopted when the isolator thickness is relatively small.
By the way, in the conventional isolator and the mounting structure thereof shown in
FIGS. 13A and 13B
, the isolator and the preceding stage circuits are connected together via conductor patterns formed on the printed circuit board. Therefore, there have been the following problems.
1) The pattern for connecting the isolator and the preceding stage circuits together needs to be designed to have excellent matching for preventing a loss in signal delivery.
2) For the same reason, every time when changing any of the thickness and material of the printed circuit board, the shape of the conductor pattern, or the part arrangement of the isolator or the preceding stage circuit, as well as when changing electrical characteristics of the isolator or the preceding stage circuit, the patterns for connecting between the isolator and the preceding stage circuits have to be redesigned.
3) Even when the connecting pattern is designed to have most excellent matching, there will be certainly produced various kinds of losses such as losses due to radiation from the conductor pattern, dielectric losses of the printed circuit board, conductor losses of the conductor pattern, and losses due to reflection in an incomplete matching portion. Also, even when the above-mentioned design is completely performed, there are manufacturing scattered values of the connecting pattern in shape and size and the printed circuit board in thickness and permitivity, so that matching incompletion cannot be avoided due to the dispersion. Furthermore, when a dielectric material of the printed circuit board absorbs atmospheric moisture, dielectric losses in the connecting pattern may increase. Unnecessary radiation generated from the connecting pattern may also produce a malfunction by interference with other circuits on the printed circuit board. In particular, the place surely capable of producing the internal mutual interference is the pattern portion connecting between a heavy-duty isolator such as a signal transmission portion of radio-communication equipment such as a portable telephone and the preceding stage circuits, i.e., an electric power amplifier.
4) The connecting pattern is arranged on the printed circuit board between the isolator and the preceding stage circuit requiring an area for this position to occupy, so that the position becomes dead spots so as to have difficulty in miniaturizing the entire device.
In the isolator and the mounting structure thereof shown
FIGS. 14A
to
15
B, there are the following problems other than the problems 1) to 4).
5) The printed circuit board is required to have the opening for fitting the isolator thereinto, so that unless the opening is simple shaped, a mold is needed causing increase in cost.
6) The earth block for connecting the grounding conductor on the bottom face of the isolator is needed on the bottom of the printed-circuit-board opening for fitting the isolator thereinto so as to have difficulty in miniaturization and reduction in weight of the entire apparatus such as a communication unit.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a nonreciprocal circuit device that solves various problems such as losses, unnecessary radiation, and the internal mutual interference, which are produced at a connecting point between the nonreciprocal circuit device and a circuit to be connected thereto, and also to provide a mounting structure of the nonreciprocal circuit device capable of promoting reduction in losses, size, and weight by facilitating matching with the circuit to be connected thereto.
A nonreciprocal circuit device according to the present invention comprises a case having a substantially rectangular parallelepiped shape, an input terminal group disposed in juxtaposition at a first height from a first side of a mounting surface of the case, and an output terminal group disposed in juxtaposition at a second height from a second side opposite to the first side of the mounting surface, wherein the first and the second height are different from each other. By this structure, the input terminal group or the output terminal group can be directly connected to connecting pads on a circuit board according to the height of the circuit board having circuits to be connected to the nonreciprocal circuit device.
The first height may be located at one of an intermediate height of the case and the top-face height of the case, and the second height may be substantially the same height as the bottom surface of the case. By this structure, the output terminal group is directly connected to a printed circuit board for mounting the nonreciprocal circuit device, and the input terminal group can be directly connected to connecting pads on the top surface of a module circuit board of preceding stage circuits to be mounted on the printed circuit board.
The height of the input terminal group may be determined by according to the thickness of the module circuit board forming the preceding stage circuits, so that the input terminal group of the nonreciprocal circuit device and the connecting pads of the module circuit board are of equal height in a state that the module circuit board and the nonreciprocal circuit device are mounted on the printed circuit board, thereby eliminating dead spots and reducing the
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
Norris Jeremy
Paladini Albert W.
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