Power amplifier

A power amplifier comprising a main power amplifier and a subsidiary power amplifier having an idle current smaller than idle current of the main power amplifier, and operated by switching the main power amplifier and the subsidiary power amplifier, wherein:

• each of the main power amplifier and the subsidiary power amplifier comprises a former amplification element for amplifying RF signals, a latter amplification element for amplifying output signals from the former amplification element, a former bias circuit for driving the former amplification element, and a latter bias circuit for driving the latter amplification element;
• spacing between the former amplification element of the main power amplifier and the former amplification element of the subsidiary power amplifier is not more than 50 μm;
• and
• spacing between the former amplification element of the main power amplifier and the former bias circuit of the subsidiary power amplifier is not less than 100 μm.

A power amplifier comprising a main power amplifier and a subsidiary power amplifier having an idle current smaller than idle current of the main power amplifier, and operated by switching the main power amplifier and the subsidiary amplifier, wherein:

• each of the main power amplifier and the subsidiary power amplifier comprises a former amplification element for amplifying RF signals, a latter amplification element for amplifying output signals from the former amplification element, a former bias circuit for driving the former amplification element, and a latter bias circuit for driving the latter amplification element;
• the latter amplification element of the main power amplifier comprises a first latter amplification element and a second latter amplification element;
• spacing between each of the first and second latter amplification element and the latter amplification elements of the subsidiary power amplifier is not more than 100 μm;
• and
• spacing between each of the first and second latter amplification elements and the latter bias circuit of the subsidiary power amplifier is not less than 200 μm.