Systems and methods for duplexer circuits having signal cancellation paths

A method of duplexing radio frequency signals, the method comprising:

• outputting a radio frequency transmit signal to a first transmit filter positioned between a power amplifier and an antenna;
• amplifying a leakage signal at a first low-noise amplifier received from the first transmit filter via a first receive filter, the leakage signal caused by the radio frequency transmit signal;
• receiving the radio frequency transmit signal at a cancellation path including a second receive filter and a second transmit filter;
• receiving a cancellation signal caused by the radio frequency transmit signal travelling through the cancellation path at a second low-noise amplifier;
• and
• applying a phase shift to one or both of the leakage signal and the cancellation signal.

A radio frequency system comprising:

• a power amplifier configured to amplify radio frequency transmit signals;
• a duplexer circuit including a first transmit filter configured to receive a radio frequency transmit signal from the power amplifier, a first receive filter configured to receive, via the first transmit filter, a leakage signal caused by the radio frequency transmit signal, and a cancellation path configured to receive the radio frequency transmit signal from the power amplifier;
• an antenna configured to receive the radio frequency transmit signal from the first transmit filter;
• first and second low-noise amplifiers, the first low-noise amplifier configured to receive the leakage signal from the first receive filter and amplify the leakage signal, and the second low-noise amplifier configured to receive a cancellation signal caused by the radio frequency transmit signal travelling through the cancellation path;
• and
• a phase shifter configured to apply a phase shift to one or both of the leakage signal and the cancellation signal.