Power amplifier

A power amplifier comprising:

• a first amplifier configured to output a signal based on a difference between an input signal and a feedback signal;
• a second amplifier configured to amplify power of the signal output from the first amplifier and output the amplified signal;
• a first feedback circuit configured to feed the signal output from the second amplifier back to the first amplifier;
• a third amplifier configured to amplify power of the signal output from the second amplifier and output the amplified signal;
• and
• a second feedback circuit configured to feed the signal output from the third amplifier back to the first amplifier,
• wherein the feedback signal is a signal obtained by combining an output signal of the first feedback circuit with an output signal of the second feedback circuit,
• wherein the first amplifier includes:
• a first resistive element,
• a first transistor,
• a second transistor,
• a first constant current source, and
• a first output terminal,
• wherein the first output terminal is connected to a first potential line through the first resistive element,
• wherein the first output terminal is connected to one terminal of the first constant current source through the first transistor,
• wherein the other terminal of the first constant current source is connected to a second potential line,
• wherein the one terminal of the first constant current source is connected to the first potential line through the second transistor,
• wherein the input signal is supplied to a control terminal of the first transistor, and
• wherein the feedback signal is supplied to a control terminal of the second transistor.