Audio signal amplifier and audio apparatus having the same

摘要

To provide an audio signal amplifier and an audio apparatus having the same that automatically set the output level to an optimum level depending on power supply voltage and so on. The audio signal amplifier of the present invention has an input terminal for receiving an audio signal from outside; a demodulating level control signal input terminal for receiving a demodulating level control signal; a variable-gain amplifying circuit for inputting a gain control signal and the audio signal and amplifying the audio signal at an amplifying factor in response to the gain control signal; a demodulating circuit for receiving the output signal of the variable-gain amplifying circuit and a demodulating signal feedback amount control signal and outputting a demodulating signal obtained by demodulating the output signal of the variable-gain amplifying circuit, the demodulating signal varying in level in response to the demodulating signal feedback amount control signal, as the gain control signal; a control circuit for adjusting demodulating level for outputting the demodulating signal feedback amount control signal generated in response to the demodulating level control signal; and a first output terminal for outputting the output signal of the variable-gain amplifying circuit.