A power amplifier for amplifying a radio frequency signal, comprising: an envelope tracking power supply (206, 207) for receiving the radio frequency signal and providing an output comprising a combination of: an alternating current component provided by a linear modulator of the envelope tracking power supply; and a direct current component provided by an external direct current power supply; a carrier amplifier coupled with the envelope tracking power supply (206, 207) and configured to amplify the radio frequency signal; an input matching network configured to split the amplified radio frequency signal from the carrier amplifier such that a first part of the amplified radio frequency signal passes along a peak amplifier path and a second part of the amplified radio frequency signal passes along an impedance transformer path; a peak amplifier coupled with the envelope tracking power supply and configured to amplify the first part of the amplified radio frequency signal from the input matching network; an impedance transformer configured to perform impedance transformation on the second part of the amplified radio frequency signal from the input matching network; an output matching network configured to combine the output of the peak amplifier and the impedance transformer, wherein the peak amplifier is configured to be switched off in a lower power mode and switched on in a high power mode by the output of the tracking power supply, based at least in part on an input power level of the radio frequency signal; wherein the carrier amplifier is connected in series with the peak amplifier through the input matching network and the output matching network and the input impedance of the peak amplifier is designed to obtain an optimum load modulation at the carrier amplifier. an envelope tracking power supply (206, 207) for receiving the radio frequency signal and providing an output comprising a combination of: an alternating current component provided by a linear modulator of the envelope tracking power supply; and a direct current component provided by an external direct current power supply; a carrier amplifier coupled with the envelope tracking power supply (206, 207) and configured to amplify the radio frequency signal; an input matching network configured to split the amplified radio frequency signal from the carrier amplifier such that a first part of the amplified radio frequency signal passes along a peak amplifier path and a second part of the amplified radio frequency signal passes along an impedance transformer path; a peak amplifier coupled with the envelope tracking power supply and configured to amplify the first part of the amplified radio frequency signal from the input matching network; an impedance transformer configured to perform impedance transformation on the second part of the amplified radio frequency signal from the input matching network; an output matching network configured to combine the output of the peak amplifier and the impedance transformer, wherein the peak amplifier is configured to be switched off in a lower power mode and switched on in a high power mode by the output of the tracking power supply, based at least in part on an input power level of the radio frequency signal; wherein the carrier amplifier is connected in series with the peak amplifier through the input matching network and the output matching network and the input impedance of the peak amplifier is designed to obtain an optimum load modulation at the carrier amplifier.