Balun

Abstract

A balun capable of a reduced whole size. The balun includes an input line receiving an unbalanced signal, an output line receiving the unbalanced signal from the input line and outputting a balanced signal, and a ground part. The input and output lines are formed on a layer, and the ground part is formed on a different layer from the layer. The ground part includes an opening and is electrically connected to the input line, and a portion of the ground part is removed to form the opening so that a potential difference occurs between first and second output lines. Thus, although a length of the output line is less than ¼ of an input wavelength λ, a difference between phases of first and second output signals can be about 180°. As a result, the whole size of the balun can be reduced.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects of the present invention will be more apparent by describing certain exemplary embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a related art a balance-to-unbalance (balun);

FIG. 2 is a cross-sectional view taken along line I-I′ of FIG. 1;

FIG. 3 is a perspective view of a balun according to a first exemplary embodiment of the present invention;

FIG. 4 is a plan view of the balun shown in FIG. 3;

FIG. 5 is a cross-sectional view taken along line II-II′ of FIG. 4;

FIG. 6 is an enlarged perspective view of part A shown in FIG. 3;

FIG. 7 is a graphical representation of phases of output signals output from first and second output ports shown in FIG. 4;

FIG. 8 is a graphical representation of magnitudes of the output signals output from the first and second output ports shown in FIG. 4;

FIG. 9 is a plan view of a balun according to a second exemplary embodiment of the present invention;

FIG. 10 is a cross-sectional view taken along line III-III of FIG. 9;

FIG. 11 is an enlarged perspective view of part B shown in FIG. 9;

FIG. 12 is a perspective view of a balun according to a third exemplary embodiment of the present invention;

FIG. 13 is a cross-sectional view taken along line IV-IV′ of FIG. 12;

FIG. 14 is an enlarged perspective view of part C of FIG. 12;

FIG. 15 is a perspective view of a balun according to a fourth exemplary embodiment of the present invention;

FIG. 16 is a graphical representation of magnitudes of the output signals output from the output ports of FIG. 15;

FIG. 17 is a perspective view of a balun according to a fifth exemplary embodiment of the present invention;

FIG. 18 is a sectional view taken on line V-V′ of FIG. 17; and

FIG. 19 is a sectional view taken on line VI-VI′ of FIG. 17.

Claims

1. A balance-to-unbalance (balun) comprising: a substrate;a first signal line formed on the substrate and transmitting an input signal;a second signal line formed on a layer of the substrate on which the first signal line is formed, receiving the input signal from the first signal line, and outputting first and second output signals having different phases;a ground part formed on a different layer from the layer on which the first and second signal lines are formed, comprising an opening, and electrically connected to the first signal line, wherein a portion of the ground part is removed to form the opening so that a potential difference occurs between a path of the second signal line through which the first output signal is transmitted and a path of the second signal line through which the second output signal is transmitted; anda first dielectric layer interposed between the first and second signal lines and the ground part.

2. The balun of claim 1, wherein the first signal line comprises: a first port receiving the input signal from an external source; anda second port opposite to the first port and outputting the input signal received through the first port to the second signal line.

3. The balun of claim 2, further comprising a first conductor electrically connecting the first port to the ground part, wherein the dielectric layer comprises a first via hole, wherein a portion of the first dielectric layer is removed to form the first via hole in an area in which the second port and the ground part overlap with each other, and the first conductor is electrically connected to the first port and the ground part through the first via hole.

4. The balun of claim 3, wherein the ground part comprises: a first metal part positioned in an edge area of the substrate and having a closed-loop shape;a second metal part extending from the first metal part and facing the first and second signal lines; anda third metal part extending from the first metal part, spaced apart from the second metal part in an area facing the first port and an input port, and facing the first signal line.

5. The balun of claim 4, wherein the second metal part is electrically connected to the second port through the first conductor.

6. The balun of claim 4, wherein the second metal part and the third metal part comprise one or more branches which extend from the first metal part.

7. The balun of claim 3, wherein the ground part comprises: a first ground part electrically connected with the second port via the first conductor;a second ground part formed on the first ground part with a predetermined gap between the first and second ground parts; anda conductive member electrically connecting the first and the second ground parts, and supporting one end of the second ground part, the other end of the second ground part extending above the first ground part by a predetermined gap.

8. The balun of claim 2, wherein a width of an area of the first signal line in which the first port is formed is thicker than a width of an other area of the first signal line in which the first port is not formed.

9. The balun of claim 2, wherein the second signal line comprises: an input port positioned adjacent to the second port and receiving the input signal;a first output line extending from the input port, positioned adjacent to the first signal line, and outputting the first output signal; anda second output line extending from the input port in an opposite direction to a direction toward which the first output line extends and outputting the second output signal.

10. The balun of claim 9, wherein the input port is positioned in a center of the second signal line.

11. The balun of claim 9, wherein a length of the first signal line is equal to a sum of the lengths of the input port and the first output line.

12. The balun of claim 1, wherein a difference between phases of the first and second output signals is about 180°.

13. The balun of claim 1, further comprising at least one capacitor provided above the ground part and electrically connected to the ground part.

14. The balun of claim 13, wherein the at least one capacitor comprises: a first electrode part provided in a first area and a second area above the ground part and electrically connected to the ground part in the second area; anda second electrode part provided above the first electrode part and electrically connected to the ground part in the first area.

15. The balun of claim 14, further comprising: a second dielectric layer interposed between the ground part and the first electrode part; anda third dielectric layer interposed between the first and second electrode parts.

16. The balun of claim 15, wherein: the second dielectric layer comprises a second via hole, wherein a portion of the second dielectric layer is removed to form the second via hole so as to expose a portion of the ground part in the second area;the third dielectric layer comprises a third via hole, wherein a portion of the third dielectric layer is removed to form the third via hole so as to expose a portion of the ground part in the first area; andthe first electrode part is electrically connected to the ground part through the second via hole, and the second electrode part is electrically connected to the ground part through the third via hole.

17. The balun of claim 16, further comprising: a second conductor formed in the second via hole to electrically connect the first electrode part to the ground part; anda third conductor formed in the third via hole to electrically connect the second electrode part to the ground part.

18. The balun of claim 17, wherein an area of the first electrode part corresponding to the third conductor is removed, and the first electrode part is insulated from the third conductor.

19. The balun of claim 14, wherein the at least one capacitor further comprises: a third electrode part formed in the first and second areas above the ground part; anda fourth electrode part extending from the third electrode part in a direction orthogonal to the third electrode part, positioned in the first area, and connected to the ground part to electrically connect the ground part to the third electrode part.

20. The balun of claim 19, wherein the fourth electrode part forms a single body along with the third electrode part.

21. The balun of claim 20, further comprising a fourth dielectric interposed between the third electrode part and the ground part.

22. A balun comprising: a substrate;a first signal line comprising first and second ports and formed on the substrate to transmit an input signal, wherein the first port is formed at a first end to receive the input signal, and the second port is formed at a second end opposite to the first port to output the input signal received from the first port;a second signal line positioned adjacent to the first signal line on the substrate, crossing a center of the substrate, and comprising an output port at either end and an input port, wherein the input port is formed in an area adjacent to the second port to receive the input signal from the second port, and both ends of the second signal line output first and second output signals corresponding to the input signal and having different phases;a ground part positioned in an edge area of the substrate and comprising first, second, and third metal parts, wherein the first metal part has a closed-loop shape, the second metal part extends from the first metal part toward the center of the substrate and faces the first and second signal lines, and the third metal part extends from the first metal part toward the center of the substrate, faces the second signal line, is spaced apart from the second metal part in an area in which the input port and the second port are formed, and is electrically connected to the second port; anda dielectric interposed between the first and second signal lines and the ground part.

23. A balun comprising: a substrate;a first signal line comprising first and second ports and formed on the substrate to transmit an input signal, wherein the first port is formed at a first end to receive the input signal, and the second port is formed at a second end opposite to the first end to output the input signal received from the first port and;a second signal line positioned adjacent to the first signal line on the substrate, crossing a center of the substrate, and comprising an output port at either end and an input port formed in an area adjacent to the second port to receive the input signal from the second port, and both ends of the second signal line output first and second output signals corresponding to the input signal and having different phases;a ground part positioned in an edge area of the substrate and comprising first, second, and third metal parts, wherein the first metal part has a closed-loop shape, the second metal part extends from the first metal part toward the center of the substrate and faces the first and second signal lines, and the third metal part extends from the first metal part toward the center of the substrate, faces the second signal line, is spaced from the second metal part in an area in which the input port and the second port are formed, and is electrically connected to the second port;a dielectric interposed between the first and second signal lines and the ground part; anda capacitor provided above the ground part and comprising first and second electrode parts, wherein the first electrode part is electrically connected to the third metal part, and the second electrode part is spaced apart from the first electrode part above the first electrode part and electrically connected to the second metal part.

24. A balun comprising: a substrate;a first signal line comprising first and second ports and formed on the substrate to transmit an input signal, wherein the first port is formed at a first end to receive the input signal, and the second port is formed at a second end opposite to the first end to output the input signal received from the first port;a second signal line positioned adjacent to the first signal line on the substrate, crossing a center of the substrate, and comprising an output port at either end and an input port formed in an area adjacent to the second port to receive the input signal from the second port, and both ends of the second signal line output first and second output signals corresponding to the input signal and having different phases;a ground part positioned in an edge area of the substrate and comprising first, second, and third metal parts, wherein the first metal part has a closed-loop shape, the second metal part extends from the first metal part toward the center of the substrate and faces the first and second signal lines, and the third metal part extends from the first metal part toward the center of the substrate, faces the second signal line, is spaced from the second metal part in an area in which the input port and the second port are formed, and is electrically connected to the second port;a dielectric interposed between the first and second signal lines and the ground part; anda capacitor provided above the ground part and comprising third and fourth electrode parts, wherein the third electrode part is spaced apart from the third metal part, and the fourth electrode part extends from the third electrode part and is connected to the second metal part to electrically connect the second metal port to the third electrode part.