Variable capacitors and switches fabricated using electrowetting on dielectric techniques and related phase shifters, base station antennas and other devices
An adjustable phase shifter includes an RF signal input, an RF signal output, a first delay line, a second delay line and a first electrowetting-activated switch disposed between the RF signal input and the RF signal output.
1. An adjustable phase shifter, comprising:
a radio frequency (“RF”) signal input;
an RF signal output;
a first delay line;
a second delay line;
a first electrowetting-activated switch configured to selectively open and close an electrical path between the RF signal input and the RF signal output.
2. The adjustable phase shifter of claim 1 , further comprising a second electrowetting-activated switch, wherein the first electrowetting-activated switch is coupled between the RF signal input and a first end of the first delay line and the second electrowetting-activated switch is coupled between a second end of the first delay line and the RF signal output.
3. The adjustable phase shifter of claim 2 , further comprising a third electrowetting-activated switch and a fourth electrowetting-activated switch, wherein the third electrowetting-activated switch is coupled between the RF signal input and a first end of the second delay line and the fourth electrowetting-activated switch is coupled between a second end of the second delay line and the RF signal output.
4. The adjustable phase shifter of claim 1 , wherein the first delay line is longer than the second delay line.
5. The adjustable phase shifter of claim 1 , wherein the first electrowetting-activated switch comprises a first switch pad, a second switch pad and a first liquid metal droplet that is configured to selectively electrically connect the first switch pad to the second switch pad.
6. The adjustable phase shifter of claim 5 , wherein the first switch pad is larger than the second switch pad.
7. The adjustable phase shifter of claim 6 , wherein the first electrowetting-activated switch selectively couples the first delay line to a ground pad.
8. The adjustable phase shifter of claim 1 ,
wherein the RF signal input, the RF signal output, the first delay line, the second delay line and the first electrowetting-activated switch form a first unit cell of the adjustable phase shifter, the adjustable phase shifter including at least a second unit cell coupled in series with the first unit cell, and
wherein the first delay line of the second unit cell is longer than both the first delay line and the second delay line of the first unit cell.
9. The adjustable phase shifter of claim 1 , further comprising a hybrid coupler, wherein the RF input is coupled to a first port of the hybrid coupler, the first delay line is coupled to a second port of the hybrid coupler, the second delay line is coupled to a third port of the hybrid coupler, and the RF output is coupled to a fourth port of the hybrid coupler.
10. The adjustable phase shifter of claim 1 , wherein the first electrowetting-activated switch is configured to move a droplet of liquid metal to open or close the electrical path.
11. An adjustable phase shifter, comprising:
a radio frequency (“RF”) signal input;
an RF signal output;
a first delay line;
a first electrowetting-activated switch that is configured to selectively make and break an electrical connection between the RF signal input and a first end of the first delay line; and
a second electrowetting-activated switch that is configured to selectively make and break an electrical connection between the RF signal output and a second end of the first delay line.
12. The adjustable phase shifter of claim 11 , wherein the first electrowetting-activated switch comprises a first conductive pad, a second conductive pad and a first droplet of liquid metal that is disposed within a first container and configured to selectively electrically connect the first conductive pad to the second conductive pad.
13. The adjustable phase shifter of claim 11 , further comprising:
a second delay line;
a third electrowetting-activated switch that is disposed between the RF signal input and a first end of the second delay line; and
a fourth electrowetting-activated switch that is disposed between the RF signal output and a second end of the second delay line.
14. The adjustable phase shifter of claim 13 , wherein the fourth electrowetting-activated switch comprises a third conductive pad, a fourth conductive pad and a second droplet of liquid metal that is disposed within a second container and configured to selectively electrically connect the third conductive pad to the fourth conductive pad.
15. An adjustable phase shifter, comprising:
a hybrid coupler that has a first port coupled to a radio frequency (“RF”) input, a second port coupled to a first variable delay line, a third port coupled to a second variable delay line and a fourth port coupled to an RF output,
wherein a first length of the first variable delay line is adjustable by using electrical control signals to control a position of a droplet of liquid material along the first variable delay line.
16. The adjustable phase shifter of claim 15 , wherein the droplet of liquid material is a droplet of liquid metal.
17. The adjustable phase shifter of claim 16 , wherein the droplet of liquid metal is configured for movement to selectively couple the first variable delay line to a respective one of a plurality of ground connections.
18. A phase shifter comprising:
a first unit cell comprising first and second switches that are coupled to each other by a first delay line having a first length; and
a second unit cell comprising third and fourth switches that are coupled to each other by a second delay line having a second length that is longer than the first length,
wherein the first unit cell is coupled in series with the second unit cell, and
wherein the first unit cell further comprises a third delay line having a third length that is shorter than the first length.
19. The phase shifter of claim 18 ,
wherein the second unit cell further comprises a fourth delay line having a fourth length that is shorter than the second length.
20. The phase shifter of claim 19 , wherein the second delay line provides a delay that is about twice a delay of the first delay line.
21. The phase shifter of claim 19 , further comprising a fifth delay line that provides a delay that is four times a delay of the first delay line.
22. The phase shifter of claim 19 , further comprising a fifth delay line that provides a delay that is eight times a delay of the first delay line.
23. The phase shifter of claim 18 , wherein the phase shifter is part of a base station antenna.