Patent ID: 8917139

Claim:
A digital amplifier which amplifies a signal, comprising: a switching unit that amplifies a signal input to the digital amplifier by performing a switching operation; a driving unit that turns the switching unit on and off; an input signal detection unit that detects whether or not there is an input signal to the digital amplifier; a first control unit that performs control such that the switching unit starts a switching operation by starting driving of the driving unit, when the digital amplifier is changed from a no signal input state to a signal input state and the input signal detection unit detects an input signal to the digital amplifier, and performs control such that the switching unit stops the switching operation by stopping the driving of the driving unit, when the digital amplifier is changed from a signal input state to a no signal input state, and the input signal detection unit does not detect an input signal to the digital amplifier; modulation units that perform pulse modulation for an input signal to the digital amplifier; a feedback unit that feeds back an output signal of the switching unit to the modulation unit; and a feedback aspect changing unit that changes a feedback aspect of the feedback unit according to a detection result of the input signal detection unit.