Active cancellation of transmitter leakage in a radio receiver

A method for active transmitter leakage cancellation, comprising:

• generating a transmitter leakage cancellation signal;
• and
• injecting the transmitter leakage cancellation signal into a receive path in an upstream direction at a point in the receive path that is downstream of a receive filter having a pass-band that corresponds to a desired receive frequency band such that a noise component of the transmitter leakage cancellation signal in the pass-band of the receive filter passes through the receive filter in the upstream direction and a desired component of the transmitter leakage cancellation signal is reflected by the receive filter and propagated downstream through the receive path, wherein the receive filter is a receive filter of a duplexer coupled to an antenna, and injecting the transmitter leakage cancellation signal is such that the noise component passes through the receive filter of the duplexer and out the antenna.

A radio system, comprising:

• a receive path;
• a transmitter leakage cancellation signal generation subsystem configured to generate a transmitter leakage cancellation signal;
• a filter configured to filter the transmitter leakage cancellation signal to remove noise in a desired receive frequency band of the receive path to thereby provide a filtered transmitter leakage cancellation signal, the filter having an output coupled to a point in the receive path such that the filtered transmitter leakage cancellation signal is combined with a receive signal in the receive path to thereby cancel transmitter leakage from a corresponding radio transmitter, wherein the output of the filter is directly connected to the point in the receive path.