| CPC H03F 3/193 (2013.01) [H03G 3/3036 (2013.01); H03F 1/0277 (2013.01); H03F 1/223 (2013.01); H03F 3/191 (2013.01); H03F 2200/451 (2013.01); H03G 2201/103 (2013.01); H03G 2201/307 (2013.01)] | 14 Claims |

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1. An amplification circuit comprising:
a first amplifier connected between an input terminal to which a radio-frequency signal is input and an output terminal from which a radio-frequency signal is output; and
a second amplifier connected in parallel with the first amplifier between the input terminal and the output terminal,
wherein the first amplifier comprises a first transistor and a second transistor that are cascode connected with each other,
wherein the second amplifier comprises a third transistor,
wherein the first transistor has a first terminal that is a gate or base connected to the input terminal, a second terminal that is a source or emitter connected to ground, and a third terminal that is a drain or collector,
wherein the second transistor has a fourth terminal that is a gate or base, a fifth terminal that is a source or emitter connected to the third terminal, and a sixth terminal that is a drain or collector connected to the output terminal,
wherein the third transistor has a seventh terminal that is a gate or base connected to the input terminal, an eighth terminal that is a source or emitter connected to ground, and a ninth terminal that is a drain or collector connected to the output terminal,
wherein the amplification circuit is configured to selectively switch between amplification of a radio-frequency signal input to the input terminal using the first amplifier and amplification of the radio-frequency signal input to the input terminal using the second amplifier,
wherein a bias supplied to the first terminal and a bias supplied to the seventh terminal are different from each other, and
wherein a bias supplied to the fourth terminal and a bias supplied to the seventh terminal are different from each other.
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