| 摘要 |
To provide a small-sized high frequency power amplifier for preventing oscillation by a small number of switching circuits and outputting high power and low power with high efficiencies, a high frequency power amplifier module and a portable telephone, the high frequency power amplifier is constituted by an amplifying circuit A and an amplifying circuit B connected in parallel, a size of a transistor at an output stage of the amplifying circuit B is made to be equal to or smaller than ¼ of a size of a transistor of an output stage of the amplifying circuit A and a switching circuit is connected between a signal line forward from the output stage of the amplifying circuit A and a ground terminal. Further, when the transistor constituting the amplifying circuit B is brought into a nonoperational state and the switching circuit is made OFF, a high frequency signal of high power is outputted from the amplifying circuit A and when the transistor constituting the amplifying circuit A is brought into a nonoperational state and the switching circuit is made ON, a high frequency signal of low power is outputted from the amplifying circuit B. |
