Patent ID: 8633768

Claim:
An amplifying device comprising: an amplifier that amplifies an input signal; and an output unit that supplies an output signal, which is adjusted corresponding to an envelope signal of said input signal, to a power supply terminal of said amplifier, wherein said output unit includes: an analog amplifying circuit that amplifies said envelope signal; a digital circuit that selectively outputs a first voltage or a second voltage that is lower than said first voltage; and first and second output circuits that accept an output signal of said analog amplifying circuit and an output signal of said digital circuit, wherein said first output circuit includes: a first integrating circuit that integrates an output signal of said digital circuit; and a combining section that combines an output signal of said first integrating circuit and an output signal of said analog amplifying circuit and outputs the combined signal to a power supply terminal of said amplifier, wherein said second output circuit includes: a second integrating circuit that integrates the output signal of said digital circuit, said second integrating circuit having an impedance higher than said first integrating circuit; a resistor having two ends, one end being connected to an output terminal of said second integrating circuit, the other end being connected to an output terminal of said analog amplifying circuit, and a load connected to the output terminal of said second integrating circuit, and wherein said digital circuit outputs said first voltage in a first state where a voltage applied at the one end of said resistor is lower than the voltage applied at the other end of said resistor and said digital circuit outputs said second voltage in a second state where the voltage applied at the one end of said resistor is higher than the voltage applied at the other end of said resistor.