Dual band coupler

Details Dual band coupler Dual band coupler

2002-08-06

2004-06-29

Tokar, Michael (Department: 2819)

Wave transmission lines and networks

Plural channel systems

Having branched circuits

C333S109000, C333S238000, C333S246000

Reexamination Certificate

active

06756860

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dual band coupler and, in particular, to an improvement in design freedom of a dual band coupler, in which coupling coefficients of two main signal lines can be independently controlled.
2. Description of the Prior Art
Generally, A coupler used in a mobile telecommunication terminal device transmits a signal at a constant output through an antenna by distributing a transmitting signal in a proper ratio, or by taking a constant output signal from an amplifier of a transmitter and transmitting the signal to a automatic phase controller (APC).
With the need for multi-functional and small-sized mobile telecommunication terminal devices, dual band or triple band terminals are widely spread, which are characterized by the simultaneous service of two or more frequencies in one device. Accordingly, there is a strong demand for parts that can treat two different frequency bands. In response to such demand, dual band couplers have been developed.
In order to better understand the background of the invention, a detailed description will be given of a conventional dual band coupler in conjunction with drawings, below.
FIG. 1
is an equivalent circuit of a conventional dual band coupler. With reference to
FIG. 1
, the dual band coupler comprises a first main signal line
2
and a second main signal line
3
connected to an output amplifier of a transmitter treating different frequency band signals, and a coupling signal line
4
taking a predetermined amount of signal and adjacent to the first and second main signal line. The first and second main signal line
2
and
3
are provided with input IN
1
and IN
2
and output OUT
1
and OUT
2
terminals, and the coupling signal line
4
takes samples of input signals from different positions of the first and second main signal line
2
and
3
and transmits them to the automatic phase controller.
The dual band coupler forms a multiple layer type coupler consisting of multiple dielectric layers in order to provide a small-sized coupler.
FIG. 2
is an exploded perspective view of the conventional dual band coupler. Referring to
FIG. 2
, the dual band coupler comprises a first and fifth dielectric layer
11
and
15
having ground patterns
21
and
25
; a second and third dielectric layer
12
and
13
having the first and second main signal lines
22
a
and
22
b
,
23
a
and
23
b
; and a fourth dielectric layer
14
having coupling signal lines
24
a
and
24
c
. The second and third dielectric layers
12
and
13
comprise two laminated dielectric layers
12
a
and
12
b
,
13
a
and
13
b
, and electrode patterns formed on dielectric layers, i.e. signal lines
22
a
and
22
b
,
23
a
and
23
b
, are connected to each other through conductive via-holes h
1
and h
2
. Furthermore, the fourth dielectric layer
14
consists of two laminated dielectric layers
14
a
and
14
b
, and signal lines
24
a
,
24
b
, and
24
c
formed on the dielectric layers
14
a
and
14
b
are connected to each other through conductive via-holes h
3
and h
4
. In addition, both ends of signal lines connected to each other through via-holes are extended to edges of dielectric layers to be connected to a lateral terminal, which will be formed in a subsequent process.
However, conductive patterns constituting signal lines should be formed at different positions on dielectric layers in order to shield mutual electromagnetic interference between the first and second main signal lines. Therefore, an area, in which the signal line is formed, becomes relatively small, and so precision patterning is needed. As a result, production cost and rejection rate are increased.
Additionally, in a conventional dual band coupler of
FIG. 2
, it is hard to independently control coupling coefficients of the first
22
and second
23
main signal line. In a multiple layers type coupler, the coupling coefficient is defined as a thickness of the dielectric layer inserted between main signal lines and an inductance owing to a signal line pattern.
As described above, however, the dual band coupler does limitedly form the signal line pattern, and so the coupling coefficient cannot be desirably controlled. Also, in case of controlling the thickness of the dielectric layer, when the thickness t of the dielectric layer
14
a
of the fourth dielectric layer is controlled in order to control the coupling coefficient of the second main signal line
23
, thicknesses of dielectric layers of the first main signal line
22
and the coupling signal line
24
are also varied. Therefore, the coupling coefficient of the first main signal line
22
is considered, thereby, it is very difficult to design the desired dual band coupler having various coupling coefficients required in mobile telecommunication terminal devices.
Therefore, there remains a need for a dual band coupler, which can independently control a coupling coefficient of the first and second main signal line.
SUMMARY OF THE INVENTION
Therefore, the primary object of the present invention is to overcome the above disadvantages encountered in prior arts, and to provide a dual band coupler, which can independently control a coupling coefficient of a first and second signal line by laminating a dielectric layer having a coupling signal line between dielectric layers having a first and second main signal line so that dielectric layers between the coupling signal line and main signal lines have a different thickness from each other, or by laminating different numbers of dielectric layers between the coupling signal line and main signal lines, respectively.
Another object of the present invention is to provide a dual band coupler, which has an improved isolation by forming a shielding pattern for excluding mutual electromagnetic interference between the first and second main signal line on the dielectric layer having the coupling signal line.
Based on the present invention, the above objects can be accomplished by a provision of a dual band coupler, comprising: a first ground pattern formed on a first dielectric layer; a first main signal line having a first input and output terminal, which is a conductive pattern formed on a second dielectric layer laminated on the first dielectric layer; a coupling signal line having a coupling terminal and an isolation terminal, which is a conductive pattern formed on a third dielectric layer laminated on the second dielectric layer; a second main signal line having a second input and output terminal, which is a conductive pattern formed on a fourth dielectric layer laminated on the third dielectric layer; and a second ground pattern formed on a fifth dielectric layer laminated on the fourth dielectric layer.
According to an embodiment of the present invention, a dielectric layer between the first main signal line and the coupling signal line is made to be different in thickness from a dielectric layer between the second main signal line and the coupling signal line, or dielectric layers between the coupling signal line and the first main signal line are different in number from the dielectric layers between the coupling signal line and the second main signal line, whereby the coupling coefficient of each main signal line can be independently controlled.
According to another embodiment of the present invention, an isolation between the first and second main signal line can be improved by providing a dual band coupler further comprising a shielding pattern for excluding electromagnetic interference between the first and second main signal lines. The shielding pattern is formed around the coupling signal line on the third dielectric layer so as to be separated from the coupling signal line.
According to another embodiment of the present invention, the second, third, and fourth dielectric layers may consist of plural layers. Particularly, when the third dielectric layer comprises plural layers, the third dielectric layer comprises three or more layers consisting of a first layer having the coupling terminal, on which the first

Affiliated with

Also associated with

Rating

Dual band coupler does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Dual band coupler, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dual band coupler will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3323535