Feedforward amplifier and radio communication apparatus with the amplifier

An amplifier comprising:

• a first amplifier circuit which amplifies a first signal to output an amplified first signal;
• a circuit which outputs a second signal corresponding to a difference between the first signal and the amplified first signal;
• a second amplifier circuit which amplifies the second signal to output an amplified second signal;
• a combine circuit which outputs an amplified signal by combining the amplified second signal with the amplified first signal;
• and
• a controller which controls a supply of a power to the first amplifier circuit and the second amplifier circuit and has a first mode to supply the power to the second amplifier circuit without supplying the power to the first amplifier circuit,
• wherein the amplified signal is selected and outputted from a group of the amplified first signal, the amplified second signal and a signal reduced a distortion component from the amplified first signal by using the amplified second signal.

A feedforward amplifier comprising:

• a first amplifier circuit which amplifies a first signal to output an amplified first signal;
• a second amplifier circuit which amplifies a second signal to output an amplified second signal, the second signal corresponding to a difference between the first signal and the amplified first signal;
• and
• an output circuit which outputs an amplified signal selected from the amplified first signal, the amplified second signal and a combined signal reduced a distortion component from the amplified first signal by using the amplified second signal;
• wherein the feedforward amplifier has three operation modes comprised of a first mode to supply a power to the second amplifier circuit without supplying the power to the first amplifier circuit, a second mode to supply the power to the first amplifier circuit without supplying the power to the second amplifier circuit and a third mode to supply the power to the first amplifier circuit and the second amplifier circuit, and the output circuit outputs the amplified second signal in the first mode, the output circuit outputs the amplified first signal in the second mode and the output circuit outputs the combined signal in the third mode.