A semiconductor device is provided in which power consumption is reduced and an increase in circuit area is inhibited. The semiconductor device includes a high frequency amplifier circuit, an envelope detection circuit, and a power supply circuit. The power supply circuit has a function of supplying a power supply potential to the high frequency amplifier circuit, an output of the high frequency amplifier circuit is connected to the envelope detection circuit, and an output of the envelope detection circuit is connected to the power supply circuit. The power supply circuit can reduce the power consumption by changing the power supply potential in accordance with the output of the high frequency amplifier circuit. The use of an OS transistor in the envelope detection circuit can inhibit an increase in circuit area.