Telecommunications receiver and a transmitter

A telecommunications receiver comprising:

• a first IQ mixer and a second IQ mixer,
• means to provide a received signal to the second mixer in antiphase to the phase of the received signal provided to the first mixer, each mixer producing an I signal and a Q signal, the I signal from the second mixer being in phase or antiphase to the I signal from the first mixer, the Q signal from the second mixer being in phase or in antiphase to the Q signal from the first mixer, and
• means to produce a first output signal and means to produce a second output signal,
• the first output signal being the sum of the two I signals when the two I signals are in opposite phases or the difference between the two I signals when they are of the same phase, such that DC offset components present in the I signals at least partially cancel,
• the second output signal being the sum of the two Q signals when the two Q signals are of opposite phase or the difference between the two Q signals when they are of the same phase, such that DC offset components present in the Q signals at least partially cancel.

A method of receiving comprising:

• mixing a received signal to produce a first I signal and a first Q signal;
• mixing a signal in antiphase to the received signal to produce a second I signal and a second Q signal:
• combining the first and second I signals in accordance with the relative phases of the first and second I signals;
• and
• combining the first and second Q signals in accordance with the relative phases of the first and second Q signals;
• wherein DC offset components present in the first and second I signals at least partially cancel, and DC components present in the first and second Q signals at least partially cancel.

A method of transmitting comprising:

• mixing a Q signal and a signal in antiphase to the Q signal and an I signal and a signal in antiphase to the I signal to produce a first output signal;
• mixing in reverse order the Q signal and the signal in antiphase to the Q signal and in reverse order the I signal and the signal in antiphase to the I signal to produce a second output signal;
• combining the first and second output signals to produce a signal for transmission;
• wherein residual carrier components present in the first and second output signals at least partially cancel.