Power amplifier circuit

A power amplifier circuit comprising:

• a first amplifier configured to amplify an input signal and output an output signal;
• a second amplifier configured to, in accordance with a control signal, amplify a signal corresponding to the input signal, generate a signal having an opposite phase to a phase of the output signal, and add the signal to the output signal;
• a control circuit configured to supply the control signal to the second amplifier;
• and
• a third differential pair, the third differential pair comprising a fifth transistor and a sixth transistor,
• wherein the first amplifier comprises a first differential pair,
• wherein the second amplifier comprises a second differential pair,
• wherein the first differential pair comprises a first transistor configured to amplify a first signal and output a first amplified signal, and a second transistor that is configured to amplify a second signal and output a second amplified signal, the first signal and the second signal having opposite phases,
• wherein the second differential pair comprises a third transistor configured to, in accordance with the control signal, amplify the first signal and output a third amplified signal, and a fourth transistor configured to, in accordance with the control signal, amplify the second signal and output a fourth amplified signal,
• wherein a collector or drain of the third transistor is connected to a collector or drain of the second transistor,
• wherein a collector or drain of the fourth transistor is connected to a collector or drain of the first transistor, and
• wherein a collector or drain of the first transistor is connected to a base or gate of at least one of the fifth transistor or the sixth transistor of the third differential pair.

A power amplifier circuit comprising:

• a first amplifier configured to amplify an input signal and output an output signal;
• a second amplifier configured to, in accordance with a control signal, amplify a signal corresponding to the input signal, generate a signal having an opposite phase to a phase of the output signal, and add the signal to the output signal;
• and
• a control circuit configured to supply the control signal to the second amplifier,
• wherein the first amplifier comprises a first differential pair,
• wherein the second amplifier comprises a second differential pair,
• wherein the first differential pair comprises a first transistor configured to amplify a first signal and output a first amplified signal, and a second transistor that is configured to amplify a second signal and output a second amplified signal, the first signal and the second signal having opposite phases,
• wherein the second differential pair comprises a third transistor configured to, in accordance with the control signal, amplify the first signal and output a third amplified signal, and a fourth transistor configured to, in accordance with the control signal, amplify the second signal and output a fourth amplified signal, wherein the second differential pair further comprises a first impedance element between an emitter or source of the third transistor and ground, and a second impedance element between an emitter or source of the fourth transistor and ground,
• wherein a collector or drain of the third transistor is connected to a collector or drain of the second transistor, and
• wherein a collector or drain of the fourth transistor is connected to a collector or drain of the first transistor.