Hybrid coupler based T/R switch
A hybrid coupler-based T/R switch for use in a TDM system. An output hybrid coupler of a balanced amplifier is used to selectively switch a transmit or receive path to an antenna. During transmission, power at the output of the balanced amplifier is delivered directly to the antenna. During reception, power from the antenna is reflected through ports of the hybrid coupler connected to respective two amplifiers of the balanced amplifier, to constructively combine at a port of the coupler coupled to the receive path, with a ninety degrees phase shift. A pair of shunting switches or series switches coupled to the ports of the hybrid coupler connected to the two amplifiers, and a shunting switch coupled to the port coupled to the receive path, control operation of the hybrid coupler-based T/R switch. An additional switch coupled to the port of the coupler that is coupled to the receive path can provide a bypass path for reception or transmission through the antenna while bypassing the balanced amplifier of the transmit path and an amplifier of the receive path.
1. A circuit arrangement comprising:
i) a balanced amplifier comprising
an output hybrid coupler comprising a first port, coupled port (CPL), a second port, direct port (DIR), a third port, isolated port (ISO), and a fourth port, input port (IN), the fourth port, IN, being configured for connection to an antenna;
ii) first and second switches of a first set of switches, respectively coupled to the first port, CPL, and the second port, DIR;
iii) a third switch of the first set of switches coupled to the third port, ISO, the third switch configured to selectively couple a terminating resistor to the third port, ISO; and
iv) a fourth switch of the first set of switches coupled to the third port, ISO, the fourth switch configured to selectively couple a bypass conduction path to the third port, ISO,
wherein during a first mode of operation of the circuit arrangement:
the first and second switches are configured to respectively couple amplified phase-shifted signals of the balanced amplifier to the first port, CPL, and the second port, DIR,
the third switch is closed so as to couple the terminating resistor to the third port, ISO, and
the fourth switch is open so as to decouple the bypass conduction path from the third port, ISO.
2. The circuit arrangement according to claim 1 , wherein during a second mode of operation of the circuit arrangement:
the first and second switches are configured to:
respectively decouple the amplified phase-shifted signals from the first port, CPL, and the second port, DIR, and
respectively couple substantially identical impedances to the first port, CPL, and the second port, DIR,
the third switch and the fourth switch are open.
3. The circuit arrangement according to claim 2 , wherein during a third mode of operation of the circuit arrangement:
the first and second switches are configured to:
respectively decouple the amplified phase-shifted signals from the first port, CPL, and the second port, DIR, and
respectively couple substantially identical impedances to the first port, CPL, and the second port, DIR,
the third switch is open, and
the fourth switch is closed to couple the bypass conduction path to the third port, ISO.
4. The circuit arrangement according to claim 3 , wherein the substantially identical impedances are provided via one of: a) a short circuit to a reference ground, or b) an open circuit.
5. The circuit arrangement according to claim 4 , wherein the first and second switches are shunting switches configured to provide the short circuit to the reference ground in their respective closed states.
6. The circuit arrangement according to claim 4 , wherein the first and second switches are series switches configured to provide the open circuit in their respective open states.
7. The circuit arrangement according to claim 1 , wherein the terminating resistor is connected to the third port, ISO.
8. The circuit arrangement according to claim 4 , further comprising a low noise amplifier, LNA, coupled to the third port, ISO.
9. The circuit arrangement according to claim 8 , wherein the low noise amplifier comprises an input transistor having a gate node that is coupled to the third port, ISO, and a source node that is coupled to a degeneration inductor.
10. The circuit arrangement according to claim 9 , wherein the third switch and the fourth switch are coupled to the third port, ISO, through elements of an input match of the low noise amplifier that are coupled to the gate node of the input transistor.
11. The circuit arrangement according to claim 10 , wherein the elements of the input match comprise an inductor in series connection with a capacitor.
12. The circuit arrangement according to claim 10 , wherein the third switch is further configured to selectively couple to the third port, ISO, one or more reactive elements that are series-connected to the terminating resistor.
13. The circuit arrangement according to claim 12 , wherein the one or more reactive elements are series-connected to the degeneration inductor.
14. The circuit arrangement according to claim 12 , wherein the one or more reactive elements and the third switch are coupled between the gate node and the source node of the input transistor.
15. The circuit arrangement according to claim 10 , wherein during the second mode of operation, a combined impedance seen by the third port, ISO, looking into the low noise amplifier, is substantially equal to an impedance seen at the fourth port, IN.
16. The circuit arrangement according to claim 10 , wherein:
the first mode of operation is a transmit mode of operation for output at the fourth port, IN, a transmit RF signal based on combined amplified phase-shifted signals of the balanced amplifier that are coupled to the first port, CPL, and the second port, DIR,
the second mode of operation is a receive mode of operation for input at the fourth port, IN, a receive RF signal that is coupled to the third port, ISO, for amplification by the low noise amplifier, and
the third mode of operation is a bypass mode of operation for output or input at the fourth port, IN, of an RF signal that is coupled to the third port, ISO, and conducted through the bypass conduction path, thereby bypassing the balanced amplifier and the low noise amplifier.
17. The circuit arrangement according to claim 16 , further comprising a single-pole multi-throw RF selection switch,
wherein a first throw of the RF selection switch is coupled to an input of the balanced amplifier,
wherein a second throw of the RF selection switch is coupled to an output of the low noise amplifier, and
wherein a third throw of the RF selection switch is coupled to the bypass conduction path.
18. The circuit arrangement according to claim 7 , further comprising a switchable conduction path coupled to the third port, ISO, the switchable conduction path comprising:
a quarter wavelength transmission line based on a frequency of the signal at fourth port, IN; and
an additional shunting switch coupled at an end of the quarter wavelength transmission line away from the third port, ISO,
wherein during the first mode of operation, the additional shunting switch is closed so to provide an open seen by the third port, ISO, looking into the switchable conduction path, and
wherein during the second mode of operation, the additional shunting switch is open.
19. The circuit arrangement according to claim 18 , further comprising a low noise amplifier, LNA, coupled to the additional shunting switch.
20. The circuit arrangement according to claim 1 , further comprising an antenna connected to the fourth port, IN.
21. The circuit arrangement according to claim 1 , further comprising a second set of switches comprising first, second and third switches, wherein:
the first and second switches of the second set are respectively coupled to a first port, CPL, and as second port, DIR, of an input hybrid coupler of the balanced amplifier,
the third switch of the second set is coupled to a fourth port, IN, of the input hybrid coupler by way of a second terminating resistor.
22. The circuit arrangement according to claim 1 , wherein the circuit arrangement is monolithically integrated.
23. The circuit arrangement according to claim 22 , wherein the circuit arrangement is monolithically integrated by using a fabrication technology comprising one of: a) silicon-on-insulator (SOI) technology, or b) silicon-on-sapphire technology (SOS).
24. The circuit arrangement according to claim 1 , wherein each switch of the first set of switches is a field-effect transistor, FET, based switch comprising one or more stacked FETs.
25. The circuital arrangement according to claim 24 , wherein the one or more stacked FETs are metal-oxide-semiconductor (MOS) FETs, or complementary metal-oxide-semiconductor (CMOS) FETs.
26. The circuital arrangement according to claim 1 , wherein the circuital arrangement is adapted to transmit and receive a signal via an antenna connected at the fourth port, IN, that has a frequency equal to, or greater than, 1 GHz.
27. The circuital arrangement according to claim 1 , wherein the circuital arrangement is adapted to transmit and receive a signal via an antenna connected at the fourth port, IN, that has a frequency equal to, or greater than, 10 GHz.
28. An electronic module comprising the circuit arrangement according to claim 1 .
29. A phased array element comprising the circuit arrangement according to claim 1 .
30. A method, comprising using of the electronic module of claim 28 in one or more electronic systems comprising: a) a television, b) a cellular telephone, c) a personal computer, d) a workstation, e) a radio, f) a video player, g) an audio player, h) a vehicle, i) a medical device, or j) other electronic systems.