Outphasing amplifier

An outphasing amplifier comprising:

• a first amplifier configured to amplify a first signal;
• a second amplifier configured to amplify a second signal;
• a third amplifier configured to amplify the first signal amplified by the first amplifier;
• a fourth amplifier configured to amplify the second signal amplified by the second amplifier;
• a first impedance converter configured to have a first end connected to the first amplifier and a second end connected to the third amplifier;
• a second impedance converter configured to have a first end connected to the second amplifier and a second end connected to the fourth amplifier;
• a first matching circuit configured to match an output impedance of the first amplifier with an input impedance of the first impedance converter;
• a second matching circuit configured to match an output impedance of the second amplifier with an input impedance of the second impedance converter;
• a third matching circuit configured to match an output impedance of the first impedance converter with an input impedance of the third amplifier;
• a fourth matching circuit configured to match an output impedance of the second impedance converter with an input impedance of the fourth amplifier;
• and
• a combiner configured to combine the first signal amplified by the third amplifier and the second signal amplified by the fourth amplifier and output a combined signal as an output signal;
• wherein a first phase difference of the first signal input to the third matching circuit with respect to the first signal output from the first matching circuit is less than 90° at a center frequency of an operating frequency band, and
• a second phase difference of the second signal input to the fourth matching circuit with respect to the second signal output from the second matching circuit is more than 90° at the center frequency.