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US 7,254,244 B2Granted
Pop and click reduction using DAC power up and power down processing
AssigneeSigmatel, Inc.
InventorsMatthew Brady Henson, Matthew D. Felder
Life of this patent
Estimating the term…
Abstract
An audio amplifier generates an output to a load, in which a digital-to-analog converter drives the amplifier during powering up and powering down the amplifier. The digital-to-analog converter controls the amplifier to ramp the voltage at the output at a predetermined rate to reduce rapid voltage changes from being sent to the load during the powering up or powering down sequence.
Claims16
An apparatus comprising:
- an audio amplifier to generate an output to an audio load;
- a digital-to-analog converter to drive the audio amplifier during at least one of powering up and powering down the audio amplifier, the digital-to-analog converter to control the audio amplifier to ramp the voltage at the output at a predetermined rate to reduce audio pop and click from being heard at the load during the at least one of powering up or powering down of the audio amplifier;
- a control circuit to generate data sent to the digital-to-analog converter during at least one of powering up and powering down the audio amplifier;
- and
- a clamping switch at the output of the amplifier to selectively clamp the output of the amplifier to a power return potential, wherein the clamping switch is on to clamp the output to the return potential during initiation of a powering up sequence and the clamping switch is off when the audio amplifier and the digital-to-analog converter are substantially turned on.
2 more elements
A method to power up or power down an audio amplifier comprises:
- sending digital data for digital-to-analog conversion during a powering up or powering down of an audio amplifier, which generates an output to an audio load;
- converting the digital data to drive the audio amplifier;
- clamping of an output node of the audio amplifier to a power return potential during initiation of a powering up sequence and turning off the clamping when the audio amplifier and the digital-to-analog converter are substantially turned on;
- and
- using the converted digital data to control the ramping of the voltage at the output to not exceed a predetermined rate to reduce audio pop and click from being heard at the load during the powering up or powering down of the audio amplifier.
2 more elements
An integrated circuit comprising:
- an audio amplifier to generate an analog output to am audio load, when the audio load is operably coupled to the integrated circuit;
- a digital-to-analog converter to drive the audio amplifier during at least one of powering up and powering down the audio amplifier, the digital-to-analog converter to control the audio amplifier to ramp the voltage at the output at a predetermined rate to reduce audio pop and click from being heard at the load during the at least one of powering up or powering down of the audio amplifier;
- a control circuit to generate data sent to the digital-to-analog converter during at least one of powering up and powering down the audio amplifier;
- and
- a clamping switch at the output of the amplifier to selectively clamp the output of the amplifier to a power return potential, wherein the clamping switch is turned on to clamp the analog output to the power return potential during initiation of a powering down sequence and wherein the clamping switch is turned off when the audio amplifier and the digital-to-analog converter are substantially turned on.
2 more elements
An apparatus comprising:
- an amplifier to generate an output to a load;
- a digital-to-analog converter to drive the amplifier during at least one of powering up and of powering down the amplifier, the digital-to-analog converter to control the amplifier to ramp the voltage at the output at a predetermined rate to reduce rapid voltage changes from being sent to the load during the at least one of powering up or powering down of the amplifier;
- and
- a clamping switch at the output of the amplifier to selectively clamp the output of the amplifier to a power return potential wherein the clamping switch is turned on to clamp the output to the power return potential during initiation of a powering down sequence and wherein the clamping switch is turned off when the audio amplifier and the digital-to-analog converter are substantially turned on.
1 more element
Dependencies are inferred from the claim text.