Amplifier and communication apparatus

An amplifier for amplifying a positive-phase input signal to generate a positive-phase output signal and amplifying a negative-phase input signal to generate a negative-phase output signal, comprising:

• a first amplifier circuit to amplify the positive-phase input signal in order to obtain a first positive-phase signal and to amplify the negative-phase input signal in order to obtain a first negative-phase signal;
• and
• a second to n-th amplifier circuits, n is an integer equal to or larger than three, each includes a first amplifier unit and a second amplifier unit, the first amplifier unit amplifying the positive-phase input signal to obtain a second positive-phase signal and amplifying the negative-phase input signal to obtain a second negative-phase signal, the second amplifier unit amplifying the positive-phase input signal to obtain a third positive-phase signal and amplifying the negative-phase input signal to obtain a third negative-phase signal,
• wherein
• the positive-phase output signal is a sum of the first positive-phase signal and the second positive-phase signal of the k-th amplifier circuit (k is an integer of two or more and n or less) while the negative-phase output signal is a sum of the first negative-phase signal and the second negative-phase signal of the k-th amplifier circuit,
• or the positive-phase output signal is a sum of the first positive-phase signal and the third negative-phase signal of the k-th amplifier circuit while the negative-phase output signal is a sum of the first negative-phase signal and the third positive-phase signal of the k-th amplifier circuit.