Power amplifier

A power amplifier comprising:

• a distributor comprising an input terminal through which a first signal is provided, and being configured to output a second signal and a third signal, wherein the third signal is delayed by 2ϕ degrees from the second signal and ϕ is a real number greater than 45 and less than 90;
• a first amplifier that amplifies the second signal and outputs a fourth signal when a power level of the first signal is less than a first level;
• a second amplifier that amplifies the third signal and outputs a fifth signal when the power level of the first signal is less than a second level, the second level being greater than the first level;
• a first phase shifter to which the fourth signal is input, and which outputs a sixth signal delayed by ϕ degrees from the fourth signal;
• a second phase shifter to which the fifth signal is input, and which outputs a seventh signal advanced by about ϕ degrees from the fifth signal;
• and
• a combiner configured to combine the sixth signal and seventh signal, and output an amplified signal of the first signal, wherein:
• the first phase shifter comprises a first inductor connected in series between the first amplifier and the combiner,
• the second phase shifter comprises a first capacitor connected in series between the second amplifier and the combiner, and
• a capacitance of the first capacitor is equal to 1/(√{square root over ((n−1))}RL/ω), where n is an impedance conversion ratio of the first phase shifter, RL is an impedance as seen from an output of the first amplifier when the first and second amplifiers are turned on, and ω is an angular frequency corresponding to a center frequency of the first signal.