Power amplifier for amplifying radio frequency signal

A multi-stage power amplifier for amplifying a radio frequency signal, the multi-stage power amplifier comprising:

• an envelope tracking power supply comprising
• a linear modulator configured to receive an envelope signal and provide an alternating current component, and
• a combiner configured to receive the alternating current component from the linear modulator, receive a direct current component from an external direct current power supply, and provide an envelope tracking power supply signal comprising the alternating current component and the direct current component;
• a plurality of stages, each stage comprising:
• a carrier amplifier coupled with the envelope tracking power supply and configured to amplify the radio frequency signal, the carrier amplifier powered by the envelope tracking power supply signal;
• an input matching network configured to split the amplified radio frequency signal from the carrier amplifier such that one part of the amplified radio frequency signal passes along a peak amplifier path and another 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 one part of the amplified radio frequency signal from the input matching network, the peak amplifier powered by the envelope tracking power supply signal;
• an impedance transformer configured to perform impedance transformation on the other 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 for input to a next stage,
• wherein the peak amplifier is configured to be switched off to a lower power mode and switched on to a high power mode by the envelope tracking power supply signal based at least in part on an input power level of the radio frequency signal.

A method for amplifying a radio frequency signal, the method comprising:

• receiving an envelope signal at linear modulator and providing, an alternating current component;
• receiving the alternating current component and a direct current component from an external direct current power supply at a combiner;
• providing an envelope tracking power supply signal from the combiner, the envelope tracking power supply signal comprising the alternating current component and the direct current component;
• amplifying the radio frequency signal using a carrier amplifier, wherein the carrier amplifier is powered by the envelope tracking power supply signal;
• splitting the amplified radio frequency signal from the carrier amplifier using an input matching network such that one part of the amplified radio frequency signal passes along a peak amplifier path and another part of the amplified radio frequency signal passes along an impedance transformer path;
• amplifying the one part of the amplified radio frequency signal from the input matching network using a peak amplifier in the peak amplifier path, wherein the peak amplifier is powered by the envelope tracking power supply signal and the peak amplifier is configured to be switched off to a lower power mode and switched on to a high power mode by the envelope tracking power supply signal based at least in part on an input power level of the radio frequency signal;
• performing impedance transformation on the other part of the amplified radio frequency signal using an impedance transformer in the impedance transform path;
• and
• combining the output of the peak amplifier and the impedance transformer using an output matching network.