Power amplifier systems with balun and shunt capacitor

The power amplifier system of claim further comprising a third controllable shunt capacitor electrically connected between the output of the first power amplifier and the output of the second power amplifier.

The power amplifier system of claim wherein the power amplifier core further includes a third power amplifier and a fourth power amplifier, the power amplifier system further comprising a fourth controllable shunt capacitor electrically connected between the output of the third power amplifier and the ground voltage, a fifth controllable shunt capacitor electrically connected between the output of the fourth power amplifier and the ground voltage, and a sixth controllable shunt capacitor electrically connected between the output of the third power amplifier and the output of the fourth power amplifier.

The power amplifier system of claim wherein the power amplifier system further comprises an inverter having a first input terminal connected to the output of the third power amplifier, a second input terminal connected to the output of the fourth power amplifier, a first output terminal connected to a first end of the first winding of the balun, and a second output terminal connected to a second end of the first winding of the balun.

The power amplifier system of claim wherein the output matching circuit further includes an input side choke inductor connected between a power supply voltage and a center tap of the first winding of the balun, and a first input side termination network including a first series inductor and a first series capacitor in series between the center tap of the first winding of the balun and the ground voltage.

The power amplifier system of claim wherein the output matching circuit further includes a second input side termination network including a second series inductor and a second series capacitor in series between the center tap of the first winding of the balun and the ground voltage, the first input side termination network and the second input side termination network tuned to different frequencies.

The power amplifier system of claim wherein the output matching circuit further includes a second shunt output matching network and a series output matching network having a first terminal and a second terminal, the first shunt output matching network electrically connected between the first terminal of the series output matching network and the ground voltage, and the second shunt output matching network electrically connected between the second terminal of the series output matching network and the ground voltage.

The power amplifier system of claim wherein the first shunt output matching network includes a first inductor and a first controllable capacitor in series, the second shunt output matching network includes a second inductor and a second controllable capacitor in series, and the series output matching network includes a third inductor and a third controllable capacitor in parallel.

A mobile device comprising:

• a transceiver configured to generate a radio frequency signal;
• and
• a front-end system including a power amplifier core configured to amplify the radio frequency signal, the power amplifier core including a first power amplifier and a second power amplifier, the front-end system further including a first controllable shunt capacitor electrically connected between an output of the first power amplifier and a ground voltage, a second controllable shunt capacitor electrically connected between an output of the second power amplifier and the ground voltage, and an output matching circuit including a first shunt output matching network and a balun having a first winding electrically connected between the output of the first power amplifier and the output of the second power amplifier and a second winding electrically connected between the first shunt output matching network and the ground voltage.

The mobile device of claim wherein the front-end system further includes a third controllable shunt capacitor electrically connected between the output of the first power amplifier and the output of the second power amplifier.

The mobile device of claim wherein the power amplifier core further includes a third power amplifier and a fourth power amplifier, the front-end system further including a fourth controllable shunt capacitor electrically connected between the output of the third power amplifier and the ground voltage, a fifth controllable shunt capacitor electrically connected between the output of the fourth power amplifier and the ground voltage, and a sixth controllable shunt capacitor electrically connected between the output of the third power amplifier and the output of the fourth power amplifier.

The mobile device of claim wherein the front-end system further includes an inverter having a first input terminal connected to the output of the third power amplifier, a second input terminal connected to the output of the fourth power amplifier, a first output terminal connected to a first end of the first winding of the balun, and a second output terminal connected to a second end of the first winding of the balun.

The mobile device of claim wherein the output matching circuit further includes an input side choke inductor connected between a power supply voltage and a center tap of the first winding of the balun, and a first input side termination network including a first series inductor and a first series capacitor in series between the center tap of the first winding of the balun and the ground voltage.

The mobile device of claim wherein the output matching circuit further includes a second input side termination network including a second series inductor and a second series capacitor in series between the center tap of the first winding of the balun and the ground voltage, the first input side termination network and the second input side termination network tuned to different frequencies.

The mobile device of claim wherein the output matching circuit further includes a second shunt output matching network and a series output matching network having a first terminal and a second terminal, the first shunt output matching network electrically connected between the first terminal of the series output matching network and the ground voltage, and the second shunt output matching network electrically connected between the second terminal of the series output matching network and the ground voltage.

The mobile device of claim wherein the first shunt output matching network includes a first inductor and a first controllable capacitor in series, the second shunt output matching network includes a second inductor and a second controllable capacitor in series, and the series output matching network includes a third inductor and a third controllable capacitor in parallel.

The mobile device of claim wherein the front-end system further includes a band switch having an input electrically connected to the second terminal of the series output matching network.

The mobile device of claim wherein the front-end system further includes a plurality of band filters each connected to a corresponding output of the band switch.

The mobile device of claim further comprising an antenna, the front-end system further including an antenna switch configured to electrically connect the antenna to a selected band filter of the plurality of band filters.