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 comprising:
a power amplifier (PA) configured to provide an outbound signal at a differential output of the PA;
a low-noise amplifier (LNA) configured to receive an inbound signal at an input of the LNA; and
a self-interference cancellation module configured to generate a phase and gain adjusted outbound signal and inject the phase and gain adjusted outbound signal at the input of the LNA, wherein the self-interference cancellation module includes switches configured to adjust the phase of the outbound signal by controllably coupling passive elements between the input of the LNA and the differential output of the PA,
wherein the passive elements include a first adjustable resistance controllably coupled between a first differential end of the differential output of the PA and the input of the LNA, and a first adjustable capacitance controllably coupled between the first differential end of the differential output of the PA and the input of the LNA.
2. The apparatus of claim 1 , further comprising a digital signal processor (DSP) configured to control adjustment of the phase and gain of the outbound signal provided at the differential output of the PA based on a phase and gain of the interference from the outbound signal in the inbound signal.
3. The apparatus of claim 1 , wherein the passive elements include:
one or more first passive components, coupled between the differential output of the PA and the input of the LNA, to generate a capacitance between the differential output of the PA and the input of the LNA; and
one or more second passive components, coupled between the differential output of the PA and the input of the LNA, to generate a resistance between the differential output of the PA and the input of the LNA.
4. The apparatus of claim 3 , wherein the one or more first passive components and the one or more second passive components are configured to be adjusted to adjust the gain and phase of the outbound signal.
5. The apparatus of claim 1 , wherein the apparatus is a wireless transceiver further comprising an antenna coupled to the differential output of the PA and coupled to the input of the LNA.
6. The apparatus of claim 1 , wherein the passive elements further include:
a second adjustable resistance controllably coupled between a second differential end of the differential output of the PA and the input of the LNA; and
a second adjustable capacitance controllably coupled between the second differential end of the differential output of the PA and the input of the LNA.
7. An apparatus comprising:
a first self-interference cancellation module configured to inject a phase and gain adjusted version of a first outbound signal, provided at an output of a first power amplifier (PA), at an input of a low-noise amplifier (LNA) to cancel interference from the first outbound signal in an inbound signal; and
a second self-interference cancellation module configured to inject a phase and gain adjusted version of a second outbound signal, provided at an output of a second PA, at the input of the LNA to cancel interference from the second outbound signal in the inbound signal.
8. The apparatus of claim 7 , wherein the first self-interference cancellation module is configured to adjust the phase and gain of the first outbound signal based on a phase and gain of the interference from the first outbound signal in the inbound signal.
9. The apparatus of claim 7 , wherein the first self-interference cancellation module includes a resistance and a capacitance.
10. The apparatus of claim 9 , wherein the resistance and the capacitance are configured to be adjusted to adjust the gain and phase of the first outbound signal.
11. The apparatus of claim 7 , wherein the first self-interference cancellation module includes:
one or more first passive components, coupled between the output of the first PA and the input of the LNA, to generate a capacitance between the output of the PA and the input of the LNA; and
one or more second passive components, coupled between the output of the first PA and the input of the LNA, to generate a resistance between the output of the first PA and the input of the LNA,
wherein the one or more first passive components and the one or more second passive components are configured to be adjusted to adjust the gain and phase of the first outbound signal.
12. The apparatus of claim 7 , wherein the apparatus is a multi-input multi-output (MIMO) RF front-end, further comprising:
a first antenna coupled to the output of the first PA and the input of the LNA; and
a second antenna coupled to the output of the second PA.
13. The apparatus of claim 7 , further comprising a digital signal processor (DSP) configured to control adjustment of the phase and gain of the first outbound signal provided at the output of the first PA based on a phase and gain of the interference from the first outbound signal in the inbound signal.
14. The apparatus of claim 13 , wherein the DSP is further configured to control adjustment of the phase and gain of the second outbound signal provided at the output of the second PA based on a phase and gain of the interference from the second outbound signal in the inbound signal.
15. An apparatus comprising:
a power amplifier (PA) configured to provide an outbound signal at a differential output of the PA;
a low-noise amplifier (LNA) configured to receive an inbound signal at an input of the LNA; and
a self-interference cancellation module configured to cancel interference from the outbound signal in the inbound signal at the input of the LNA, the self-interference cancellation module comprising:
resistances, coupled using one or more corresponding first switches, between the differential output of the first PA and the input of the LNA; and
one or more capacitances, coupled using one or more corresponding second switches, between the differential output of the first PA and the input of the LNA,
wherein the resistances include a first adjustable resistance controllably coupled between a first differential end of the differential output of the PA and the input of the LNA, and a second adjustable resistance controllably coupled between a second differential end of the differential output of the PA and the input of the LNA.
16. The apparatus of claim 15 , further comprising a digital signal processor (DSP) configured to control adjustment of the phase and gain of the outbound signal based on a phase and gain of the interference from the outbound signal in the inbound signal.
17. The apparatus of claim 15 , wherein the resistances of and the one or more capacitances are configured to be adjusted to adjust the gain and phase of the outbound signal provided at the differential output of the PA.
18. The apparatus of claim 15 , wherein the apparatus is a wireless transceiver further comprising an antenna coupled to the differential output of the PA and coupled to the input of the LNA.
19. The apparatus of claim 15 , wherein the one or more capacitances include:
a first adjustable capacitance controllably coupled between the first differential end of the differential output of the PA and the input of the LNA; and
a second adjustable capacitance controllably coupled between the second differential end of the differential output of the PA and the input of the LNA.