Symmetrical dual direction coupler
A symmetric dual direction coupler has a layout that is controlled such that there is an axis of symmetry between ports and that any switches used within the dual direction coupler are also symmetrical. That is, for a dual direction coupler having a transmitted port, an input port, an isolated port, and a coupled port with switches used to control forward mode or reverse mode for the coupler, the transmitted port and the input port are symmetrical across the axis of symmetry; the isolated port and coupled port are symmetrical across the axis of symmetry; and the switch layout is symmetrical across the axis of symmetry.
1. A dual direction coupler, comprising:
a first port comprising a first pad;
a second port comprising a second pad;
a first conductive path coupling the first port to the second port, the first conductive path being symmetrical between the first port and the second port across an axis of symmetry;
a third port comprising a third pad coupled to ground;
a fourth port comprising a fourth pad, wherein the third pad and the fourth pad are positioned on the axis of symmetry; and
a second conductive path coupling the third port to the fourth port, the second conductive path electromagnetically coupled to the first conductive path, the second conductive path comprising one or more switches, the second conductive path being symmetrical across the axis of symmetry, wherein the second conductive path comprises a first portion parallel to the first conductive path, a second portion having a hexagonal shape coupled directly to the third port and a third portion coupled directly to the fourth port.
2. The dual direction coupler of claim 1 , further comprising a dielectric material positioned between the first conductive path and the second conductive path.
3. The dual direction coupler of claim 2 , wherein the first conductive path lies in a first plane and the second conductive path lies in a second plane different than the first plane.
4. The dual direction coupler of claim 2 , wherein the second conductive path is positioned at least partially over the first conductive path.
5. The dual direction coupler of claim 1 , wherein the one or more switches comprise four switches.
6. The dual direction coupler of claim 1 , wherein the one or more switches comprise:
a first switch selectively coupling the first portion to the second portion;
a second switch selectively coupling the first portion to the third portion;
a third switch selectively coupling the first portion to the third portion; and
a fourth switch selectively coupling the first portion to the second portion.
7. The dual direction coupler of claim 1 , wherein the second portion comprises a line.
8. A radio frequency (RF) front end module comprising:
a filter;
a power amplifier coupled to the filter; and
a dual direction coupler comprising:
a first port comprising a first pad coupled to the filter;
a second port comprising a second pad;
a first conductive path coupling the first port to the second port, the first conductive path being symmetrical between the first port and the second port across an axis of symmetry;
a third port comprising a third pad coupled to ground;
a fourth port comprising a fourth pad, wherein the third pad and the fourth pad are positioned on the axis of symmetry; and
a second conductive path coupling the third port to the fourth port, the second conductive path electromagnetically coupled to the first conductive path, the second conductive path comprising one or more switches, the second conductive path being symmetrical across the axis of symmetry, wherein the second conductive path comprises a first portion parallel to the first conductive path, a second portion having a hexagonal shape coupled directly to the third port, and a third portion coupled directly to the fourth port.
9. The RF front end module of claim 8 , further comprising a second filter and a second power amplifier coupled to the first port.
10. The RF front end module of claim 8 , wherein the one or more switches comprise four switches.
11. The RF front end module of claim 8 , wherein the one or more switches comprise:
a first switch selectively coupling the first portion to the second portion;
a second switch selectively coupling the first portion to the third portion;
a third switch selectively coupling the first portion to the third portion; and
a fourth switch selectively coupling the first portion to the second portion.