Patent ID: 8150064
Filing Date: 2012-04-03
Classification: H03F

Abstract:
1. An audio output device comprising: a digital/analog converter that converts a digital audio signal to an analog audio signal; a first amplifier that is activated along with the digital/analog converter and that amplifies the analog audio signal with a predetermined center voltage as a reference to provide an output signal; a second amplifier that is activated responsive to a transition of a first enable signal to a first logic level from a second logic level at a first timing subsequent to activation of the first amplifier to amplify the output signal of the first amplifier and to provide a first amplified signal, the second amplifier outputs the first amplified signal to an electricity/audio converter, and stops output of the first amplified signal to the electricity/audio converter responsive to a transition of the first enable signal to the second logic level at a third timing subsequent to the first timing; and a third amplifier that has the first amplified signal input thereto responsive to the transition of the first enable signal to the first logic level at the first timing, the third amplifier is activated responsive to a transition of a second enable signal to the first logic level from the second logic level at a second timing between the first and third timings to amplify the first amplified signal and to provide a second amplified signal, the third amplifier outputs the second amplified signal to the electricity/audio converter, and stops output of the second amplified signal to the electricity/audio converter responsive to a transition of the second enable signal to the second logic level at the third timing.