System and apparatus for a three-line balun with power amplifier bias
View Patent ↗A balun that includes a first conductor, a second conductor, and a third conductor. The first conductor has a first length. The first conductor also has a first end connected to a first balanced power amplifier output port. The second conductor has substantially the same first length. The second conductor also includes a first end connected to a second balanced power amplifier output port and a second end connected to a second end of the first conductor. The third conductor has substantially the same first length. The third conductor has a first end connected to an antenna port and a second end connected to a ground potential.
1. A balun, formed in a multi-layer structure including a plurality of metal layers, comprising:
a first conductor having a first length, formed in a first metal layer of the multi-layer structure;
a second conductor having a second length substantially similar to the first length, formed in a second metal layer of the multi-layer structure, connected to the first conductor; and
a third conductor having a third length substantially similar to the first length, formed in a third metal layer of the multi-layer structure,
wherein the second metal layer is disposed between the first metal layer and the third metal layer.
2. The balun of claim 1 , wherein the plurality of metal layers are interleaved by a plurality of insulating layers.
3. The balun of claim 2 , wherein the plurality of insulating layers includes:
a first insulating layer to separate a first ground plane and the first metal layer;
a second insulating layer to separate the first metal layer and the second metal layer;
a third insulating layer to separate the second metal layer and the third metal layer; and
a fourth insulating layer to separate the third metal layer and a second ground plane.
4. The balun of claim 1 , further comprising:
a fourth conductor, formed in a first insulating layer of the multi-layer structure, to connect the first conductor and the second conductor.
5. The balun of claim 1 , further comprising:
a fifth conductor, formed in a first insulating layer of the multi-layer structure, to connect the third conductor to a first ground plane.
6. The balun of claim 1 , wherein the first conductor includes a first end connected to a first port.
7. The balun of claim 6 , wherein the first port is coupled to a first balanced output port of a power amplifier.
8. The balun of claim 6 , wherein the second conductor includes a first end connected to a second port and a second end connected to a second end of the first conductor.
9. The balun of claim 8 , wherein the second port is coupled to a second balanced output port of a power amplifier.
10. The balun of claim 1 , wherein the third conductor includes a first end connected to an antenna port and a second end connected to a ground potential.
11. A balun formed in a multi-layer structure including a plurality of metal layers interleaved by a plurality of insulating layers comprising:
a first conductor having a first length, formed in a first metal layer of the multi-layer structure, the first conductor having a first end connected to a first port;
a second conductor having a second length substantially similar to the first length, formed in a second metal layer of the multi-layer structure, the second conductor includes:
a first end connected to a second port, and
a second end connected to a second end of the first conductor; and
a third conductor having a third length substantially similar to the first length, formed in a third metal layer of the multi-layer structure, the third conductor having a first end connected to an antenna port and a second end connected to a ground potential.
12. The balun of claim 11 , wherein the first length is substantially equal to an even multiple of the wavelength of a selected center frequency.
13. The balun of claim 11 , wherein the first length is substantially equal to one-quarter wavelength of a selected center frequency.
14. The balun of claim 11 , further comprising:
a biasing network having a fourth conductor having a first end connected to the first port and a second end connected to a bias supply.
15. The balun of claim 14 , wherein the fourth conductor has a fourth length substantially similar to the first length.
16. The balun of claim 15 , wherein the fourth length has a reactance that offsets a parasitic capacitance of at least one of the first conductor, the second conductor, the third conductor.
17. The balun of claim 11 , wherein the first conductor, the second conductor, and the third conductor are substantially vertically aligned.
18. The balun of claim 11 , wherein the multi-layer structure is bounded by a first ground plane and a second ground plane.
19. The balun of claim 18 , wherein the first ground plane and the second ground plane are separated by a distance H and the first conductor, the second conductor, and the third conductor are vertically offset less than ten times the distance H.
20. The balun of claim 11 , wherein the multi-layer structure is formed in at least one of a group of mediums consisting of LTCC, BT resin, Silicon, and FR4.