Envelope tracking for multiple power amplifiers

A mobile device comprising:

• a transceiver configured to generate a first radio frequency signal and a second radio frequency signal;
• a front end circuit including a first power amplifier configured to amplify the first radio frequency signal and to receive power from a first supply voltage, and a second power amplifier configured to amplify the second radio frequency signal and to receive power from a second supply voltage;
• and
• a power management circuit including an envelope tracker that includes a first modulator configured to generate a first output current based on an envelope of the first radio frequency signal and a plurality of regulated voltages of different voltage levels, a second modulator configured to generate a second output current based on an envelope of the second radio frequency signal and the plurality of regulated voltages, a multi-output DC-to-DC converter configured to generate a first DC voltage and a second DC voltage, a first combiner configured to combine the first DC voltage with the first output current to generate the first supply voltage, and a second combiner configured to combine the second DC voltage with the second output current to generate the second supply voltage.

A method of envelope tracking, the method comprising:

• amplifying a first radio frequency signal using a first power amplifier that receives power from a first supply voltage, and amplifying a second radio frequency signal using a second power amplifier that receives power from a second supply voltage;
• generating a first output current based on an envelope of the first radio frequency signal and a plurality of regulated voltages of different voltage levels using a first modulator, and generating a second output current based on an envelope of the second radio frequency signal and the plurality of regulated voltages using a second modulator;
• generating a first DC voltage and a second DC voltage using a multi-output DC-to-DC converter;
• and
• generating the first supply voltage by combining the first DC voltage and the first output current using a first combiner, and generating the second supply voltage by combining the second DC voltage and the second output current using a second combiner.