Front-end circuitry for coexistence of two radios sharing an antenna and a frequency band
Technologies directed to sharing an antenna and a frequency band between coexistence radios are described herein. In one device, semi-active front-end circuitry includes a directional coupler and a phase-shifter circuit coupled to two radios that use the same antenna and the same frequency band. The phase-shifter circuit and directional coupler create an isolation null at an isolated port of the directional coupler that cancels a copy of an incident wave of a transmit signal being applied at an input port of the directional coupler. The isolation null permits the second radio to receive a receive signal concurrently with the first radio transmitting the transmit signal.
1. A device comprising:
an antenna;
a first radio;
a second radio;
a directional coupler comprising a first port coupled to the first radio, a second port coupled to the second radio, a third port, and a fourth port coupled to an impedance matched load; and
a phase-shifter circuit coupled to the third port and the antenna,
wherein:
the directional coupler receives an incident wave at the first port having a first phase;
the phase-shifter circuit causes a first reflected wave at the third port to have a second phase that is 90-degrees from the first phase; and
the directional coupler outputs a second reflected wave, at the second port, that has a third phase that is 180-degrees from the first phase of the incident wave; and
the second reflected wave cancels a copy of the incident wave at the second port caused by the incident wave received at the first port.
2. The device of claim 1 , wherein the phase-shifter circuit comprises a digital phase shifter.
3. The device of claim 1 , wherein the phase-shifter circuit comprises an analog phase shifter.
4. The device of claim 1 , wherein the directional coupler and the phase-shifter circuit are integrated in a single integrated circuit.
5. The device of claim 1 , wherein the directional coupler and the phase-shifter circuit are integrated in a Silicon-on-Insulator (SOI) integrated circuit.
6. The device of claim 1 , further comprising a processor coupled to the first radio and the second radio, wherein the processor is to send a control signal to the phase-shifter circuit, wherein the control signal adjusts a first phase shift amount applied to the first reflected wave to a second phase shift amount such that the second reflected wave at the second port has the third phase that is 180-degrees from the first phase of the incident wave.
7. The device of claim 1 , wherein the second radio is to:
measure a first signal strength indicator value of a first signal transmitted by the first radio while the phase-shifter circuit is set to apply a first phase shift amount to the first reflected wave;
send a control signal to the phase-shifter circuit to change the first phase shift amount to a second phase shift amount; and
measure a second signal strength indicator value of a second signal transmitted by the first radio while the phase-shifter circuit is set to apply the second phase shift amount to the first reflected wave, wherein the second signal strength indicator value is less than the first signal strength indicator value, wherein application of the second phase shift amount to the first reflected wave results in the second reflected wave at the second port having the third phase that is 180-degrees from the first phase of the incident wave.
8. The device of claim 1 , wherein the phase-shifter circuit comprises a digital phase shifter, wherein the second radio is to perform an isolation calibration process in which the second radio:
listens for packets transmitted by the first radio; and
adjusts, via a control signal sent from the second radio to the phase-shifter circuit, a phase shift amount until a signal strength indicator value of the packets is a lowest signal strength indicator value that results from adjusting the phase shift amount or until the signal strength indicator value is below a threshold value.
9. A Radio Frequency (RF) front-end circuit comprising:
a directional coupler comprising a first port coupled to a first radio, a second port coupled to a second radio, a third port, and a fourth port coupled to an impedance matched load; and
a phase-shifter circuit comprising a fifth port coupled to the third port and a sixth port coupled to an antenna, wherein the directional coupler receives an incident wave at the first port having a first phase, wherein the phase-shifter circuit is calibrated to cause a first reflected wave at the third port to have a second phase that is 90-degrees from the first phase, and wherein the directional coupler outputs a second reflected wave, at the second port, that has a third phase that is 180-degrees from the first phase of the incident wave, canceling a copy of the incident wave that is present at the second port caused by the incident wave received at the first port.
10. The RF front-end circuit of claim 9 , wherein the phase-shifter circuit comprises a digital phase shifter.
11. The RF front-end circuit of claim 9 , wherein the phase-shifter circuit comprises an analog phase shifter.
12. The RF front-end circuit of claim 9 , wherein the directional coupler and the phase-shifter circuit are integrated in a single integrated circuit.
13. The RF front-end circuit of claim 9 , wherein the directional coupler and the phase-shifter circuit are integrated in a Silicon-on-Insulator (SOI) integrated circuit.
14. The RF front-end circuit of claim 9 , wherein the phase-shifter circuit comprises a control input that receives a control signal, wherein the control signal adjusts a first phase shift amount applied to the first reflected wave to a second phase shift amount applied to the first reflected wave such that the second reflected wave at the second port has the third phase that is 180-degrees from the first phase of the incident wave.
15. A device comprising:
a first radio;
a second radio; and
a radio frequency (RF) front-end circuit comprising a first port coupled to the first radio, a second port coupled to the second radio, a third port, and a fourth port coupled to an impedance matched load, wherein the RF front-end circuit is configured to:
receive an incident wave at the first port having a first phase;
cause a first reflected wave at the third port to have a second phase that is 90-degrees from the first phase; and
output a second reflected wave, at the second port, that has a third phase that is 180-degrees from the first phase of the incident wave, canceling a copy of the incident wave that is present at the second port caused by the incident wave received at the first port.
16. The device of claim 15 , wherein the RF front-end circuit further comprises:
a directional coupler; and
a phase-shifter circuit that causes the first reflected wave at the third port to have the second phase.
17. The device of claim 16 , wherein the phase-shifter circuit comprises a digital phase shifter.
18. The device of claim 16 , wherein the directional coupler and the phase-shifter circuit are integrated in a single integrated circuit.
19. The device of claim 15 , wherein the RF front-end circuit comprises a control input that receives a control signal, wherein the control signal adjusts a first phase shift amount applied to the first reflected wave to a second phase shift amount applied to the first reflected wave such that the second reflected wave, at the second port, has the third phase that is 180-degrees from the first phase of the incident wave.
20. The device of claim 15 , further comprising a processor coupled to the first radio and the second radio, wherein the processor is to send a control signal to RF front-end circuit, wherein the control signal adjusts a first phase shift amount applied to the first reflected wave to a second phase shift amount such that the second reflected wave, at the second port, has the third phase that is 180-degrees from the first phase of the incident wave.