Self-interference cancellation for full-duplex communication using a phase and gain adjusted transmit signal
View Patent ↗The present disclosure is directed to an apparatus and method for cancelling self-interference caused by full-duplex communication. In a full-duplex communication device, the receiver will generally experience significant self-interference from the full-duplex communication device's own transmitter transmitting a strong outbound signal over the same channel that the receiver is to receive a weak inbound signal. The apparatus and method are configured to adjust a phase and gain of the outbound signal provided at the output of a power amplifier (PA) and inject the phase and gain adjusted outbound signal at the input of a low-noise amplifier (LNA) to cancel the interference from the outbound signal in the inbound signal.
1. An apparatus configured to cancel interference, from an outbound signal provided at an output of a power amplifier (PA), in an inbound signal at an input of a low-noise amplifier (LNA), the apparatus comprising:
a first resistor controllably coupled between a first differential end of the output of the PA and the input of the LNA;
a first capacitor controllably coupled between the first differential end of the output of the PA and the input of the LNA;
a second resistor controllably coupled between a second differential end of the output of the PA and the input of the LNA; and
a second capacitor controllably coupled between the second differential end of the output of the PA and the input of the LNA.
2. The apparatus of claim 1 , wherein resistances of the first and second resistors and capacitances of the first and second capacitors are configured to be adjusted to adjust a gain and a phase of the outbound signal.
3. The apparatus of claim 2 , wherein, to adjust the phase of the outbound signal between 0-90 degrees or 270-360 degrees, the first resistor is coupled between the first differential end of the output of the PA and the input of the LNA and the second resistor is not coupled between the second differential end of the output of the PA and the input of the LNA.
4. The apparatus of claim 2 , wherein to adjust the phase of the outbound signal between 90-270 degrees, the second resistor is coupled between the second differential end of the output of the PA and the input of the LNA and the first resistor is not coupled between the first differential end of the output of the PA and the input of the LNA.
5. The apparatus of claim 2 , wherein, to adjust the phase of the outbound signal between 0-180 degrees, the first capacitor is coupled between the first differential end of the output of the PA and the input of the LNA and the second capacitor is not coupled between the second differential end of the output of the PA and the input of the LNA.
6. The apparatus of claim 2 , wherein, to adjust the phase of the outbound signal between 180-360 degrees, the second capacitor is coupled between the second differential end of the output of the PA and the input of the LNA and the first capacitor is not coupled between the first differential end of the output of the PA and the input of the LNA.
7. The apparatus of claim 1 , further comprising:
a processor configured to adjust a phase of the outbound signal between 0-90 degrees by:
coupling the first resistor between the first differential end of the output of the PA and the input of the LNA;
coupling the first capacitor between the first differential end of the output of the PA and the input of the LNA;
not coupling the second resistor between the second differential end of the output of the PA and the input of the LNA, and
not coupling the second capacitor between the second differential end of the output of the PA and the input of the LNA.
8. The apparatus of claim 1 , further comprising:
a processor configured to adjust a phase of the outbound signal between 90-180 degrees by:
not coupling the first resistor between the first differential end of the output of the PA and the input of the LNA;
coupling the first capacitor between the first differential end of the output of the PA and the input of the LNA;
coupling the second resistor between the second differential end of the output of the PA and the input of the LNA, and
not coupling the second capacitor between the second differential end of the output of the PA and the input of the LNA.
9. The apparatus of claim 1 , further comprising:
a processor configured to adjust a phase of the outbound signal between 180-270 degrees by:
not coupling the first resistor between the first differential end of the output of the PA and the input of the LNA;
not coupling the first capacitor between the first differential end of the output of the PA and the input of the LNA;
coupling the second resistor between the second differential end of the output of the PA and the input of the LNA, and
coupling the second capacitor between the second differential end of the output of the PA and the input of the LNA.
10. The apparatus of claim 1 , further comprising:
a processor configured to adjust a phase of the outbound signal between 270-360 degrees by:
coupling the first resistor between the first differential end of the output of the PA and the input of the LNA;
not coupling the first capacitor between the first differential end of the output of the PA and the input of the LNA;
not coupling the second resistor between the second differential end of the output of the PA and the input of the LNA, and
coupling the second capacitor between the second differential end of the output of the PA and the input of the LNA.
11. The apparatus of claim 1 , wherein the first resistor and the first capacitor are connected in parallel with each other, having corresponding input terminals directly connected together at the first differential end of the output of the PA.
12. The apparatus of claim 1 , wherein the second resistor and the second capacitor are connected in parallel with each other, having corresponding input terminals directly connected together at the second differential end of the output of the PA.
13. A method for canceling interference, from an outbound signal provided at an output of a power amplifier (PA), in an inbound signal at an input of a low-noise amplifier (LNA), the method comprising:
adjusting a phase of the outbound signal between 0-90 degrees by coupling a first resistor between a first differential end of the output of the PA and the input of the LNA and coupling a first capacitor between the first differential end of the output of the PA and the input of the LNA;
adjusting the phase of the outbound signal between 90-180 degrees by coupling a second resistor between a second differential end of the output of the PA and the input of the LNA and coupling the first capacitor between the first differential end of the output of the PA and the input of the LNA;
adjusting the phase of the outbound signal between 180-270 degrees by coupling the second resistor between the second differential end of the output of the PA and the input of the LNA and coupling a second capacitor between the second differential end of the output of the PA and the input of the LNA; and
adjusting the phase of the outbound signal between 270-360 degrees by coupling the first resistor between the first differential end of the output of the PA and the input of the LNA and coupling the second capacitor between the second differential end of the output of the PA and the input of the LNA.
14. The method of claim 13 , further comprising:
adjusting the phase of the outbound signal based on a phase of the interference from the outbound signal in the inbound signal.
15. The method of claim 13 , further comprising:
adjusting resistances of the first and second resistors and capacitances of the first and second capacitors to adjust a gain and a phase of the outbound signal provided at the output of the PA.
16. The method of claim 13 , wherein the inbound signal and the outbound signal are at a same carrier frequency.
17. An apparatus comprising:
a processor; and
a self-interference cancellation module configured to cancel interference from an outbound signal provided at an output of a power amplifier (PA) in an inbound signal at an input of a low-noise amplifier (LNA), the self-interference cancellation module comprising:
a first resistor controllably coupled by the processor between a first differential end of the output of the PA and the input of the LNA,
a first capacitor controllably coupled by the processor between the first differential end of the output of the PA and the input of the LNA,
a second resistor controllably coupled by the processor between a second differential end of the output of the PA and the input of the LNA, and
a second capacitor controllably coupled by the processor between the second differential end of the output of the PA and the input of the LNA.
18. The apparatus of claim 17 , wherein the processor is configured to adjust a phase of the outbound signal between 0-90 degrees by coupling the first resistor between the first differential end of the output of the PA and the input of the LNA and coupling the first capacitor between the first differential end of the output of the PA and the input of the LNA.
19. The apparatus of claim 17 , wherein the processor is configured to adjust a phase of the outbound signal between 90-180 degrees by coupling the second resistor between the second differential end of the output of the PA and the input of the LNA and coupling the first capacitor between the first differential end of the output of the PA and the input of the LNA.
20. The apparatus of claim 17 , wherein the processor is configured to adjust a phase of the outbound signal between 180-270 degrees by coupling the second resistor between the second differential end of the output of the PA and the input of the LNA and coupling the second capacitor between the second differential end of the output of the PA and the input of the LNA.
21. The apparatus of claim 17 , wherein the processor is configured to adjust a phase of the outbound signal between 270-360 degrees by coupling the first resistor between the first differential end of the output of the PA and the input of the LNA and coupling the second capacitor between the second differential end of the output of the PA and the input of the LNA.