Digital phase shifter
Phase shifters such as networks that can be used in MMIC (Monolithic Microwave Integrated Circuit) and hybrid digital phase shifters, for low loss, wide bandwidth, and high linearity. A digital phase shifter includes input port for receiving signals and output ports for transmitting the signals. Multiple transmission lines are arranged between the input and output ports of the phase shifter. The transmission lines are arranged in a ring with first pair of the transmission lines which are arranged in series in a first path and second pair of the transmission lines arranged in series in a second path. One of the transmission lines of the first and second pairs include quarter-wave hybrid coupled line with coupled-ports and through-ports terminated in short-circuit. Hybrid coupled line can be a Lange coupler with or without RF crossover.
1. A digital phase shifter, comprising:
an input port configured to receive signals;
an output port configured to transmit phase shifted signals; and
a plurality of transmission lines disposed between the input port and the output port, wherein:
the transmission lines disposed in a ring with a first pair of the transmission lines disposed in series in a first path and a second pair of the transmission lines disposed in series in a second path, and
a selected one of the transmission lines of the first and second pairs comprising a quarter-wave hybrid coupled line.
2. The digital phase shifter as recited in claim 1 , wherein:
the transmission lines are a quarter-wave hybrid coupled line electrically disposed between the input port and the output port,
a plurality of terminations electrically connected to the quarter-wave hybrid coupled line at opposing ends, and
each terminations configured to be a shunt inductor in a first state and a shunt capacitor in a second state.
3. The digital phase shifter as recited in claim 1 , wherein the selected transmission line comprises a 3-dB hybrid coupled line.
4. The digital phase shifter as recited in claim 1 , wherein the selected transmission line comprises a Lange coupler.
5. The digital phase shifter as recited in claim 4 , wherein the Lange coupler comprises an RF crossover.
6. The digital phase shifter as recited in claim 5 , wherein:
the selected transmission line comprises coupled-ports and through-ports terminated in short-circuits, and
the short-circuits configured to reflect a signal through the selected transmission line with a natural 180-degree phase shift at different frequencies, thereby creating a phase inversion.
7. The digital phase shifter as recited in claim 6 , wherein the selected transmission line is configured to combine the signals reflected by the short-circuits to create a 270-degree phase shift, wherein 90-degrees comes from the quarter-wave length of the selected transmission line and 180 degrees coming from the natural 180-degree phase shift.
8. The digital phase shifter as recited in claim 1 , wherein the selected transmission line comprises coupled-ports and through-ports terminated in short-circuits, the short-circuits configured to reflect a signal through the selected transmission line with a natural 180-degree phase shift at different frequencies, thereby creating a phase inversion.
9. The digital phase shifter as recited in claim 8 , wherein the selected transmission line is configured to combine the signals reflected by the short-circuits to create a 270 degree phase shift, wherein 90 degrees coming from the quarter-wave length of the selected transmission line and 180 degrees coming from the natural 180-degree phase shift.
10. The digital phase shifter as recited in claim 1 , wherein the selected transmission line comprising:
four metal strips disposed in parallel to one another, with a first pair of the metal strips electrically connected to ground by a first airbridge structure, and
a second pair of the metal strips electrically connected to ground by a second airbridge structure.
11. The digital phase shifter as recited in claim 1 , comprising a pair of FETs configured to steer a signal in different directions around the ring between the input and output ports.
12. The digital phase shifter as recited in claim 11 , wherein each FET is disposed in electrical communication with a respective inductor that resonates the capacitance of each respective FET.
13. A reflection-type digital phase shifter, comprising:
an input port configured to receive signals;
an output port; and
a quarter-wave hybrid coupled line electrically disposed between the input port and the output port, wherein:
a plurality of terminations electrically connected to the quarter-wave hybrid coupled line at opposing ends thereof, and
each terminations configured to be a shunt inductor in a first state and a shunt capacitor in a second state.
14. The reflection-type digital phase shifter as recited in claim 13 , wherein:
the quarter-wave hybrid coupled line comprises a plurality of transmission lines disposed between the input port and the output port,
the transmission lines disposed in a ring with a first pair of the transmission lines disposed in series in a first path and a second pair of the transmission lines disposed in series in a second path, and
a selected one of the transmission lines of the first and second pairs comprising a quarter-wave hybrid coupled line.
15. The reflection-type digital phase shifter as recited in claim 13 , wherein each termination of the plurality of terminations comprising a switch to select between the first state and the second state.
16. The reflection-type digital phase shifter as recited in claim 13 , wherein the quarter-wave hybrid coupled line comprising:
four metal strips disposed in parallel to one another, with a first pair of the four metal strips electrically connected to the input port, and
a second pair of the metal strips electrically connected to the output port.
17. The reflection-type digital phase shifter as recited in claim 16 , wherein the first pair of the four metal strips is electrically connected to the input port by an airbridge structure.
18. The reflection-type digital phase shifter as recited in claim 13 , wherein the quarter-wave hybrid coupled line comprises a 3-dB coupled line.
19. The reflection type digital phase shifter as recited in claim 13 , wherein the quarter-wave hybrid coupled line comprises a Lange coupler.
20. The reflection type digital phase shifter as recited in claim 19 , wherein the Lange coupler comprises an RF crossover.