Mixed signal low noise interference cancellation
RF communication systems with interference cancellation for coexistence are provided herein. In certain embodiments, an RF communication system includes a transmitter that transmits a transmit signal through a first front end circuit, a receiver that processes a receive signal from a second front end circuit, and a feedback receiver that processes a feedback signal from the first front end circuit to generate a digital interference cancellation signal that compensates the receiver for interference arising from the transmitter.
1. A wireless device comprising:
a first transceiver configured to generate a first radio frequency transmit signal and to receive a first radio frequency receive signal;
a first front end system including a first power amplifier configured to receive the first radio frequency transmit signal at an input, a first low noise amplifier configured to provide the first radio frequency receive signal at an output, and a first multi-throw switch having a first throw connected to an output of the first power amplifier, a second throw connected to an input of the first low noise amplifier, and a third throw connected to a feedback path; and
a second transceiver configured to receive a second radio frequency receive signal, the second transceiver further configured to process a radio frequency feedback signal from the feedback path to generate a digital interference cancellation signal that compensates the second radio frequency receive signal for interference.
2. The wireless device of claim 1 wherein the second transceiver includes a receiver configured to generate a digital receive signal based on the second radio frequency receive signal, and to generate a compensated digital receive signal based on digitally compensating the digital receive signal with the digital interference cancellation signal.
3. The wireless device of claim 1 wherein the first multi-throw switch is configured to provide the radio frequency feedback signal to the feedback path in a first mode, and to not provide the radio frequency feedback signal to the feedback path in a second mode.
4. The wireless device of claim 1 further comprising a second multi-throw switch and a diversity front-end module configured to receive the radio frequency feedback signal from the feedback path through the second multi-throw switch.
5. The wireless device of claim 1 wherein the second transceiver includes a feedback receiver configured to process the radio frequency feedback signal.
6. The wireless device of claim 1 wherein the first transceiver is a Wi-Fi transceiver, and the second transceiver is a cellular transceiver.
7. The wireless device of claim 1 wherein the digital interference cancellation signal compensates for interference arising from at least one of adjacent channel leakage, harmonic interference, or intermodulation distortion.
8. The wireless device of claim 1 wherein the first front end system includes a filter along the feedback path and configured to filter the radio frequency feedback signal.
9. The wireless device of claim 8 wherein the filter is a diplexer.
10. The wireless device of claim 8 wherein the first front end system further includes an attenuator along the feedback path and configured to attenuate the radio frequency feedback signal.
11. The wireless device of claim 8 wherein the filter is configured to filter a carrier frequency of the first radio frequency transmit signal.
12. The wireless device of claim 1 wherein the second transceiver is further configured to generate a second radio frequency transmit signal, the wireless device further including a second front end system including a second power amplifier configured to receive the second radio frequency transmit signal at an input and a second low noise amplifier configured to provide the second radio frequency receive signal at an output.
13. A method of interference cancellation in a radio frequency communication system, the method comprising:
generating a first radio frequency transmit signal and receiving a first radio frequency receive signal using a first transceiver;
receiving the first radio frequency transmit signal at an input of a first power amplifier of a first front end system, the first power amplifier having an output connected to a first throw of a first multi-throw switch of the first front end system;
providing the first radio frequency receive signal at an output of a first low noise amplifier of the first front end system, the first low noise amplifier having an input connected to a second throw of the first multi-throw switch; and
receiving a second radio frequency receive signal using a second transceiver, and processing a radio frequency feedback signal from a feedback path to generate a digital interference cancellation signal that compensates the second radio frequency receive signal for interference, the feedback path connected to a third throw of the first multi-throw switch.
14. The method of claim 13 further comprising filtering the radio frequency feedback signal using a filter along the feedback path.
15. The method of claim 14 further comprising attenuating the radio frequency feedback signal using an attenuator along the feedback path.
16. A radio frequency communication system comprising:
an antenna;
a first multi-throw switch coupled to the antenna, the first multi-throw switch having a first throw, a second throw, and a third throw;
a first power amplifier having an input configured to receive a first radio frequency transmit signal and an output connected to the first throw;
a first low noise amplifier having an input connected to the second throw and an output configured to provide a first radio frequency receive signal;
a transceiver configured to receive a second radio frequency receive signal; and
a feedback path configured to provide a radio frequency feedback signal from the third throw to the transceiver, the transceiver configured to generate a digital interference cancellation signal based on the radio frequency feedback signal, and to compensate the second radio frequency receive signal for interference based on the digital interference cancellation signal.
17. The radio frequency communication system of claim 16 further comprising a filter along the feedback path and configured to filter the radio frequency feedback signal.
18. The radio frequency communication system of claim 17 wherein the filter is a diplexer.
19. The radio frequency communication system of claim 17 further comprising an attenuator along the feedback path and configured to attenuate the radio frequency feedback signal.
20. The radio frequency communication system of claim 17 wherein the filter is configured to filter a carrier frequency of the first radio frequency transmit signal.