Abstract: A transceiver circuit includes: a transmit path with at least one of each of a digital to analog converter converting a digital input signal to an analog signal, a filter, a first frequency synthesizer, a mixer to produce an RF output, and an amplifier amplifying the RF output for transmission; and a receive path with at least one of each of a second amplifier amplifying a received RF input, a second frequency synthesizer, a second mixer to produce a baseband signal, a second filter, and an analog to digital converter converting the baseband signal to a digital output signal; at least one switch selectively connecting different points of the circuit thereby to bypass at least one component of the circuit; and a control input connected to the switch to receive control signals for controlling operation of the switch.

Abstract: An RF transceiver apparatus comprises transmitter circuitry arranged to convert signals from a baseband frequency to RF transmission frequencies and receiver circuitry arranged to convert signals from RF reception frequencies to the baseband frequency. The transmitter and receiver circuitry each comprise three mixers arranged to convert a signals between the baseband frequency, a first intermediate frequency; a second intermediate frequency that is higher than the transmission frequencies; and a second intermediate frequency to the transmission frequency.