A multicarrier-radio transmitter internally using at least three frequency levels, baseband, an intermediate frequency, IF, and a radio frequency, RF, and comprising: a digital signal processor to produce a multicarrier signal at the IF, and a transmit amplifier circuit to amplify and transmit the multicarrier signal at the RF, the transmit amplifier circuit forming a feedback loop comprising a forward path and a reverse path, wherein the multicarrier signal at the IF is an input signal to the transmit amplifier circuit; wherein the feedback loop comprises: - a subtractor to receive the multicarrier IF input signal from the digital signal processor and a fed-back signal from the reverse path at the IF and to provide a feedback-corrected signal at the IF; - an I/Q demodulator in the forward path to down-convert the feedback-corrected multicarrier signal from the IF to baseband; - a loop-filter system in the forward path at baseband; - an I/Q modulator in the forward path to up-convert the baseband multicarrier signal from baseband to the RF; - a power amplifier in the forward path to amplify the RF signal to be transmitted via an antenna; - a pick-off node to pick off the RF multicarrier signal after the power amplifier; - a down converter in the reverse path to down-convert the picked-off RF multicarrier signal from the RF to the IF. a digital signal processor to produce a multicarrier signal at the IF, and a transmit amplifier circuit to amplify and transmit the multicarrier signal at the RF, the transmit amplifier circuit forming a feedback loop comprising a forward path and a reverse path, wherein the multicarrier signal at the IF is an input signal to the transmit amplifier circuit; wherein the feedback loop comprises: - a subtractor to receive the multicarrier IF input signal from the digital signal processor and a fed-back signal from the reverse path at the IF and to provide a feedback-corrected signal at the IF; - an I/Q demodulator in the forward path to down-convert the feedback-corrected multicarrier signal from the IF to baseband; - a loop-filter system in the forward path at baseband; - an I/Q modulator in the forward path to up-convert the baseband multicarrier signal from baseband to the RF; - a power amplifier in the forward path to amplify the RF signal to be transmitted via an antenna; - a pick-off node to pick off the RF multicarrier signal after the power amplifier; - a down converter in the reverse path to down-convert the picked-off RF multicarrier signal from the RF to the IF. - a subtractor to receive the multicarrier IF input signal from the digital signal processor and a fed-back signal from the reverse path at the IF and to provide a feedback-corrected signal at the IF; - an I/Q demodulator in the forward path to down-convert the feedback-corrected multicarrier signal from the IF to baseband; - a loop-filter system in the forward path at baseband; - an I/Q modulator in the forward path to up-convert the baseband multicarrier signal from baseband to the RF; - a power amplifier in the forward path to amplify the RF signal to be transmitted via an antenna; - a pick-off node to pick off the RF multicarrier signal after the power amplifier; - a down converter in the reverse path to down-convert the picked-off RF multicarrier signal from the RF to the IF.