Electricity: conductors and insulators – Conduits – cables or conductors – Preformed panel circuit arrangement
Reexamination Certificate
1998-11-04
2001-03-27
Sough, Hyung-Sub (Department: 2841)
Electricity: conductors and insulators
Conduits, cables or conductors
Preformed panel circuit arrangement
C333S247000, C333S202000, C333S206000, C174S250000
Reexamination Certificate
active
06207906
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to printed circuit boards (PCBs) and, in particular, to a PCB that does not alter the characteristics of a radio frequency (RF) band pass filter (BPF) mounted thereon, and a method for making the same.
2. Description of the Related Art
In general, all the elements of a radio communications system are mounted on a PCB. For example, an RF BPF is separately procured and mounted on the PCB.
FIGS. 1A and 1B
are top and bottom perspective views of an RF BPF, respectively, to which the present invention is applied. Here, the RF BPF is a dielectric filter, which is mounted on a PCB as shown in
FIG. 2
by soldering. That is, an input terminal (IN)
10
, an output terminal (OUT)
20
, and three terminals
31
,
32
, and
33
of a ground terminal (GND)
30
of the BPF are mounted on an IN
40
, and OUT
50
, and three terminal
61
,
62
and
63
of a GND
60
of the PCB, respectively.
When the dielectric RF BPF shown in
FIGS. 1A and 1B
is mounted on the PCB of
FIG. 2
, capacitance components exist between the IN
10
and the GND
30
, and between the OUT
20
and the GND
30
due to the dielectric constant &egr; of the PCB. As a result, the characteristics of the BPF are altered. Thus, despite designing the BPF to satisfy characteristic requirements for an intended application, the BPF cannot reliably operate when mounted on the PCB (due to e.g., loss increase and changed center frequency).
FIGS. 3 and 4
are Smith charts illustrating the characteristics of the RF BPF when unmounted and mounted, respectively. The BPF characteristics shown in
FIG. 3
meet the intended application requirements. However, the characteristics of the BPF become unsatisfactory when the BPF is mounted on the PCB. In the former case (FIG.
3
), the impedance of the BPF is at an inductance location of the chart as indicated by wave “A”, and the frequency bandwidth is wide as indicated by wave “B”. On the other hand, in the latter case (FIG.
4
), the impedance of the BPF includes more capacitance components as indicated by wave “A”, and the frequency bandwidth becomes narrow as indicated by wave “B”. Thus, while it is desirable for the RF BPF to exhibit the characteristics shown in
FIG. 3
when the BPF is mounted on the PCB, the characteristics nonetheless change to those shown in FIG.
4
. The changes to the characteristics arc attributable to the dielectric constant of the PCB material as described above. While the changes to the characteristics of the BPF can be prevented by re-designing the BPF, a redesign imposes serious constraints on a designer.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a printed circuit board (PCB) that does not alter the characteristics of a radio frequency (RF) band pass filter (BPF) mounted thereon, and a method for making the same.
It is another object of the present invention to provide a PCB having a dielectric constant that has no influence on the characteristics of an R BPF mounted thereon, and a method for making the same.
It is still another object of the present invention to provide a PCB that does not significantly alter the impedance of an RF BPF mounted thereon, and a method of making the same.
It is a further object of the present invention to provide a PCB that does not narrow the frequency bandwidth of an RF BPF mounted thereon, and a method for making the same.
In one aspect of the invention, a PCB for mounting a dielectric RF BPF thereon, the filter having an input terminal, an output terminal, and a ground terminal including a first, a second, and a third terminal, comprises: a first terminal for mounting the input terminal of the RF BPF thereon; a second terminal for mounting the output terminal of the RF BPF thereon, said second terminal disposed horizontally apart from said first terminal by a predetermined distance; a third terminal for mounting the first terminal of the ground terminal of the RF BPF thereon, said third terminal disposed between said first and said second terminals; a fourth terminal for mounting the second terminal of the ground terminal of the RF BPF thereon, said fourth terminal disposed vertically apart from said first terminal by a predetermined distance; a fifth terminal for mounting the third terminal of the ground terminal of the RF BPF thereon, said fish terminal disposed vertically apart from said second terminal by a predetermined distance; a first hole formed between said first and said third terminals of the PCB in a PCB thickness direction; a second hole between said second and said third terminals of the PCB in the PCB thickness direction; a third hole between said first and said fourth terminals of the PCB in the PCB thickness direction; and a fourth hole between said second and said fifth terminals of the PCB in the PCB thickness direction.
These and other objects, features and advantages of the present invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings, where the same reference numerals are used to represent the same functional elements.
REFERENCES:
patent: 4004256 (1977-01-01), Duncan
patent: 4357647 (1982-11-01), Hadersbeck et al.
patent: 5343176 (1994-08-01), Hasler
patent: 5506554 (1996-04-01), Ala-Kojola
Cuneo Kamand
Dilworth & Barrese LLP
Samsung Electronics Co,. Ltd.
Sough Hyung-Sub
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