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US 6,784,816 B2Granted
Circuits, systems and methods for volume control in 1-bit digital audio systems
AssigneeCirrus Logic, Inc.
InventorsJohn Laurence Melanson, Jason Powell Rhode
Life of this patent
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Abstract
A method of amplitude control in a 1-bit digital system includes the step of scaling the stream of 1-bit data by a scaling factor corresponding to a selected output amplitude. The scaled data is modulated and the resulting modulated, scaled data is converted from digital to analog form.
Claims22
A method of volume control in a 1-bit digital system, comprising the steps of:
- in response to an external control signal, scaling a stream of 1-bit data by a scaling factor substantially continuously applied and selectively representing a constant greater than one corresponding to a selected output amplitude to implement audio volume control;
- modulating the scaled data to generate multiple-bit recoded data;
- and
- converting the multiple-bit recoded scaled data from digital to analog form.
1 more element
A digital to analog conversion subsystem for converting a 1-bit audio data stream into analog audio comprising:
- a scaler for digitally scaling the 1-bit digital audio data to generate scaled digital data, the scaler substantially continuously applying a scaling factor selected in response to a volume control signal received from an external source to set an audio output volume level;
- a noise shaping modulator with a low pass signal transfer function for modulating the scaled 1-bit digital data and outputting multiple-bit recoded scaled data;
- and
- a multiple-bit digital to analog converter for converting the multiple-bit recoded scaled digital data analog audio data.
1 more element
An audio system, comprising:
- a source of a 1-bit audio data stream;
- a digital to analog conversion subsystem for converting the 1-bit audio data stream into analog form operable to:
- substantially continuously scale the stream of 1-bit data by a user-selected scaling factor corresponding to a selected output amplitude to provide output audio volume control, the user-selected scaling factor selectively representing a constant greater than one;
- modulate the scaled data in a noise shaping modulator with a low pass signal transfer function outputing multiple-bit requantized scaled data;
- convert the multiple-bit requantized scaled data from digital to analog form;
- and
- circuitry for converting the analog data into output audio of a user-selected volume level.
4 more elements
A method of performing volume control in an audio system, comprising:
- in response to an external control signal, continuous scaling a received stream of one-bit digital audio data by a volume control scaling greater than one;
- and modulating the scaled data to generate multi-bit recoded data;
- and
- converting the multiple-bit recorded of digital audio data into analog form.
1 more element
Dependencies are inferred from the claim text.