Radio frequency communication systems with interference cancellation for coexistence
Radio frequency (RF) communication systems with interference cancellation for coexistence are provided herein. In certain embodiments, an RF communication system includes a transmitter including a power amplifier that amplifies an RF transmit signal, a receiver including a low noise amplifier (LNA) that amplifies an RF receive signal, and an interference cancellation circuit that selects a bandpass filter from a plurality of bandpass filters to filter the RF transmit signal after amplification by the power amplifier. The selected bandpass filter operates in combination with a controllable gain circuit and a controllable phase circuit to generate an analog interference cancellation signal that is injected into the receiver to compensate the RF receive signal for interference arising from the transmitter.
1 . A mobile device comprising:
a transmitter including a power amplifier configured to amplify a radio frequency transmit signal;
a first receiver including a first low noise amplifier configured to amplify a first radio frequency receive signal; and
an interference cancellation circuit including a first controllable gain circuit, a first controllable phase circuit, a plurality of bandpass filters, and a pair of multi-throw switches configured to select a bandpass filter from the plurality of bandpass filters to filter the radio frequency transmit signal after amplification by the power amplifier, the selected bandpass filter configured to operate in combination with the first controllable gain circuit and the first controllable phase circuit to generate a first analog interference cancellation signal that is injected into the first receiver to compensate the first radio frequency receive signal for interference arising from the transmitter.
2 . The mobile device of claim 1 wherein the bandpass filter is selected based on a carrier frequency of the radio frequency transmit signal.
3 . The mobile device of claim 1 wherein the plurality of bandpass filters each have a filtering characteristics associated with a different frequency band.
4 . The mobile device of claim 1 wherein the transmitter is a cellular transmitter and the first receiver is a WiFi receiver.
5 . The mobile device of claim 1 wherein the bandpass filter is configured to filter a carrier frequency of the radio frequency transmit signal.
6 . The mobile device of claim 5 wherein the bandpass filter is configured to pass an adjacent channel leakage ratio noise of the radio frequency transmit signal.
7 . The mobile device of claim 1 wherein the first receiver detects an amount of interference, and controls at least one of the first controllable gain circuit or the first controllable phase circuit based on the detected amount of interference.
8 . The mobile device of claim 1 further comprising a second receiver including a second low noise amplifier configured to amplify a second radio frequency receive signal, the interference cancellation circuit configured to inject a second analog interference cancellation signal into the second receiver to compensate the second radio frequency receive signal for interference arising from the transmitter.
9 . The mobile device of claim 8 wherein the interference cancellation circuit further includes a second controllable gain circuit and a second controllable phase circuit, the bandpass filter configured to operate in combination with the second controllable gain circuit and the second controllable phase circuit to generate the second analog interference cancellation signal.
10 . The mobile device of claim 1 further comprising a first antenna configured to transmit the amplified radio frequency transmit signal and a second antenna configured to receive the first radio frequency receive signal.
11 . A method of interference cancellation in a mobile device, the method comprising:
amplifying a radio frequency transmit signal using a power amplifier of a transmitter;
amplifying a first radio frequency receive signal using a first low noise amplifier of a first receiver;
filtering the radio frequency transmit signal after amplification by the power amplifier using a bandpass filter selected from a plurality of bandpass filters using a pair of multi-throw switches;
generating a first analog interference cancellation signal using the bandpass filter, a first controllable gain circuit, and a first controllable phase circuit; and
injecting the first analog interference cancellation signal into the first receiver to compensate the first radio frequency receive signal for interference arising from the transmitter.
12 . The method of claim 11 further comprising selecting the bandpass filter based on a carrier frequency of the radio frequency transmit signal.
13 . The method of claim 11 further comprising filtering a carrier frequency of the radio frequency transmit signal using the bandpass filter.
14 . The method of claim 13 further comprising passing an adjacent channel leakage ratio noise of the radio frequency transmit signal using the bandpass filter.
15 . The method of claim 11 further comprising detecting an amount of interference using the first receiver, and controlling at least one of the first controllable gain circuit or the first controllable phase circuit based on the detected amount of interference.
16 . The method of claim 11 further comprising amplifying a second radio frequency receive signal using a second low noise amplifier of a second receiver, and injecting a second analog interference cancellation signal into the second receiver to compensate the second radio frequency signal for interference arising from the transmitter.
17 . The method of claim 16 generating the second analog interference cancellation signal using the bandpass filter, a second controllable gain circuit, and a second controllable phase circuit.
18 . An interference compensation system for a mobile device, the interference compensation system comprising:
a power amplifier configured to amplify a radio frequency transmit signal;
a first low noise amplifier configured to amplify a first radio frequency receive signal; and
an interference cancellation circuit including a first controllable gain circuit, a first controllable phase circuit, a plurality of bandpass filters, and a pair of multi-throw switches configured to select a bandpass filter from the plurality of bandpass filters to filter the radio frequency transmit signal after amplification by the power amplifier, the bandpass filter configured to operate in combination with the first controllable gain circuit and the first controllable phase circuit to generate a first analog interference cancellation signal that compensates the first radio frequency receive signal for interference.
19 . The interference compensation system of claim 18 wherein the bandpass filter is configured to filter a carrier frequency of the radio frequency transmit signal.
20 . The interference compensation system of claim 19 wherein the bandpass filter is configured to pass an adjacent channel leakage ratio noise of the radio frequency transmit signal.