Wave transmission lines and networks – Plural channel systems – Having branched circuits
Reexamination Certificate
2000-12-05
2003-04-01
Bettendorf, Justin P. (Department: 2817)
Wave transmission lines and networks
Plural channel systems
Having branched circuits
C336S170000
Reexamination Certificate
active
06542047
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to hybrid splitters and more particularly to microwave 90 degree splitters.
2. Description of the Related Art
Conventional ninety degree couplers are typically large, having a footprint substantially larger than two inches by two inches.
A conventional 90 degree splitter is shown in FIG.
1
. It consists of two transformers T
1
and T
2
and four capacitors C
1
, C
2
, C
3
and C
4
. Typically, the transformer is made by winding twisted wires onto a one hole toroid core. Transformer T
1
has wires
11
and
12
. Transformer T
2
has wires
13
and
14
. The connection between two transformers is usually made by soldering the wires from the two transformers together with solder joints SJ
1
and SJ
2
and then to a grounded capacitor C
3
, C
4
or welding the wires to a common metal pad which has a capacitor connected to a ground G.
Various examples of power splitters are known in the art. U.S. Pat. Nos. 4,789,845, 4,173,742, 4,182,996 and 5,430,418 show power splitters.
As the frequency of operation increases, the values of the capacitors goes down and it becomes difficult to realize them as lumped elements. In general C
3
and C
4
are smaller than C
1
and C
2
.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a ninety degree splitter that incorporates no capacitors.
It is an object of the present invention to provide a wire wound, wide band ninety degree splitter that is functional above one gigahertz.
The present invention is a ninety degree splitter which covers a wide frequency range of 1500 to 2500 MHz in a small footprint of only 0.2 inches by 0.2 inches. This device does not use any capacitors which greatly simplifies the construction and lowers the cost in comparison to conventional splitters.
The capacitors are eliminated by substituting inter-winding capacitance in the transformers used in the splitter. This eliminates the capacitors, and reduces related process such as extra soldering and welding. The result is a lower cost device with high frequency performance exceeding that obtained with conventional devices utilizing lumped capacitors.
The present invention provides a power splitter that includes a transformer with a core. A first winding (
21
), a second winding (
23
), a third winding (
22
) and a fourth winding (
24
) are wound on the core. The first and second windings are coupled to the third and fourth windings, such that the inter-winding capacitance between the windings form a third and fourth capacitance in FIG.
1
. C
3
and C
4
are eliminated in lower frequency application.
A further embodiment of the present invention provides a power splitter that includes a transformer with a core. A first winding (
31
), a second winding (
32
) and a third winding (
33
) are wound on the core. The first winding is coupled to the second winding, such that the inter-winding capacitance between the first and second winding forms a first and a second capacitance. The inter-winding capacitance between the first, the second and third winding forms a third and a fourth capacitance in FIG.
1
. All four capacitors are eliminated in high frequency applications.
REFERENCES:
patent: 3869585 (1975-03-01), Snyder
patent: 5280648 (1994-01-01), Dobrovolny
patent: 57-68917 (1982-04-01), None
Chen Lu
Ji Daxiong
Setty Radha
Bettendorf Justin P.
Mini-Circuits
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