A method of calibrating a transceiver circuit including transmission circuitry for processing an input signal to produce an output signal including the input signal modulated onto a carrier signal, and reception circuitry arranged to take a modulated signal including a signal modulated onto a carrier signal and to output the signal demodulated from the carrier signal. The method includes: selectively coupling the transmission circuitry to the reception circuitry; introducing a reference signal into the transmission circuitry, the reference signal causing a plurality of components of different frequencies to be present in a calibration signal in the reception circuitry; measuring the power, and typically the received signal strength indication (RSSI) of the calibration signal including the plurality of components; and adjusting operation of the transmission and reception circuitry to increase the amplitude of a first set of the components relative to the amplitude of a second set of the components.