Patent ID: 7020293

Claim:
An audio output device comprising: a digital attenuator operable to receive an audio input signal and to generate an audio output signal, said digital attenuator having a capability of gradually changing an output digital value of the audio output signal from a first digital value to a second digital value regardless of the audio input signal; a D/A converter coupled to said digital attenuator, said D/A converter being operable to convert the audio output signal to an analog signal; and an operational amplifier coupled to said D/A converter, said operational amplifier being operable to amplify the analog signal; wherein, said digital attenuator is operable to gradually change the output digital value from a digital value corresponding to a ground level to a digital value corresponding to a signal ground value during a power on, gradually change the output digital value from a value corresponding to the signal ground value to the digital value corresponding to the ground level during a power down or a system reset, and pass the audio output signal therethrough during a time other than the power on, power down and system reset.