Modulated audio amplifier output enable control
First Claim
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1. A method of controlling the output of an audio amplifier, the method comprising:
- receiving an indication to enable or disable the output of the audio amplifier;
controlling the output of the audio amplifier between an enabled state and a disabled state using a control signal that enables and disables the output of the audio amplifier;
transitioning between the disabled state and the enabled state of the audio amplifier in response to the indication, by modulating the control signal according to an enabled state duration and a disabled state duration respectively corresponding to the enabled state and the disabled state of the audio amplifier; and
adjusting the enabled state duration and the disabled state duration to cause a transition between a fully disabled state and a fully enabled state of the audio amplifier, whereby audible transients caused by changing whether the audio amplifier is in the disabled state or the enabled state are reduced or eliminated.
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Abstract
A modulated amplifier output enable control eliminates audible pops when enabling and disabling an audio amplifier output stage. The output of the audio amplifier is transitioned between an enabled state and a disabled state using a modulated control signal that enables and disables the output of the audio amplifier. Durations of the enabled state vs. the disabled state of the amplifier are adjusted to cause a transition between a fully disabled state and a fully enabled state of the audio amplifier so that the transition between the disabled state and the enabled state of the amplifier output is inaudible.
14 Citations
21 Claims
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1. A method of controlling the output of an audio amplifier, the method comprising:
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receiving an indication to enable or disable the output of the audio amplifier; controlling the output of the audio amplifier between an enabled state and a disabled state using a control signal that enables and disables the output of the audio amplifier; transitioning between the disabled state and the enabled state of the audio amplifier in response to the indication, by modulating the control signal according to an enabled state duration and a disabled state duration respectively corresponding to the enabled state and the disabled state of the audio amplifier; and adjusting the enabled state duration and the disabled state duration to cause a transition between a fully disabled state and a fully enabled state of the audio amplifier, whereby audible transients caused by changing whether the audio amplifier is in the disabled state or the enabled state are reduced or eliminated. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An audio amplifier circuit, comprising:
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an audio output stage comprising one or more first transistors for supplying current from corresponding power supply rails; and a control circuit for controlling whether the one or more first transistors is in an enabled or disabled state in response to a control signal, wherein the control circuit controls a transition between a disabled state and an enabled state of the audio output stage by modulating the control signal according to a disabled state duration corresponding to the disabled state of audio output stage and an enabled state duration corresponding to the enabled state of the audio output stage, wherein the control circuit adjusts the enabled state duration and the disabled state duration to cause a transition between a fully disabled state and a fully enabled state of the audio output stage, whereby audible transients caused by changing whether the audio output stage is in the disabled state or the enabled state are reduced or eliminated. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 21)
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19. An integrated circuit, comprising:
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an audio output stage having an enable input; and a control circuit for controlling whether the audio output stage is in an enabled or disabled state in response to a control signal, wherein the control circuit controls a transition between a disabled state and an enabled state of the audio output stage by modulating the control signal according to a disabled state duration corresponding to the disabled state of audio output stage and an enabled state duration corresponding to the enabled state of the audio output stage, wherein the control circuit adjusts the enabled state duration and the disabled state duration to cause a transition between a fully disabled state and a fully enabled state of the audio output stage, whereby audible transients caused by changing whether the audio output stage is in the disabled state or the enabled state are reduced or eliminated. - View Dependent Claims (20)
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Specification