Power amplifier systems with balun and shunt capacitor

A method of radio frequency signal amplification in a mobile device, the method comprising:

• generating a radio frequency input signal using a transceiver;
• amplifying the radio frequency input signal using a plurality of power amplifier stages operating in parallel with one another;
• driving an input side of a balun using the plurality of power amplifier stages, the plurality of power amplifier stages including a first power amplifier stage having a first output coupled to the first shunt capacitor and to a first input terminal on the input side of the balun, and a second power amplifier stage having a second output coupled to a second input terminal on the input side of the balun;
• and
• providing termination using a first input side termination network including a first series inductor and a first series capacitor in series between a center tap of the input side of the balun and a ground voltage, and a second input side termination network including a second series inductor and a second series capacitor in series between the center tap and the ground voltage.

A radio frequency module comprising:

• a module substrate;
• a balun on the module substrate and having an input side and an output side, the input side of the balun including a first input terminal and a second input terminal;
• a first input side termination network including a first series inductor and a first series capacitor in series between a center tap of the input side of the balun and a ground voltage, and a second input side termination network including a second series inductor and a second series capacitor in series between the center tap and the ground voltage;
• a first shunt capacitor;
• and
• a semiconductor chip attached to the module substrate and including a plurality of power amplifier stages configured to operate in parallel with one another to amplify the radio frequency input signal, the plurality of power amplifier stages including a first power amplifier stage having a first output coupled to the first shunt capacitor and to the first input terminal of the balun, and a second power amplifier stage having a second output coupled to the second input terminal of the balun.