Transmitter and receiver circuits

An RF transceiver apparatus comprising transmitter circuitry arranged to receive transmission signals at a transmitter baseband frequency and to convert the signals from the transmitter baseband frequency to a transmission frequency, and receiver circuitry arranged to receive signals at a reception frequency and to convert the received signals from the reception frequency to a receiver baseband frequency, wherein:

• the transmitter circuitry comprises a first digital local oscillator and at least one first mixer arranged to provide frequency conversion between the transmitter baseband frequency and a transmitter intermediate frequency;
• the receiver circuitry comprises a second digital local oscillator and at least one second mixer arranged to provide frequency conversion between a receiver intermediate frequency and the receiver baseband frequency;
• the transmitter circuitry comprises at least one third mixer arranged to receive a local oscillator signal and provide frequency conversion of the signal for transmission between the transmitter intermediate frequency and the transmission frequency;
• the receiver circuitry comprises at least one fourth mixer arranged to receive a local oscillator signal and provide frequency conversion of the received signal between the reception frequency and the receiver intermediate frequency;
• and
• a third local oscillator arranged to produce an RF oscillator signal and connected to the at least one third mixer and the at least one fourth mixer to provide the local oscillator signal for each of them.