Anti-noise signal generator
AssigneeDialog Semiconductor GmbH
InventorsAshley Hughes, Wessel Harm Lubberhuizen
Life of this patent
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Abstract
An anti-noise signal generator and a method of generating an anti-noise signal are presented. The anti-noise generator includes a first microphone input to receive a first sigma-delta modulated signal at a microphone sampling frequency. The first microphone input is coupled to a combiner via a first path and a second path. The combiner is adapted to combine a first filtered signal from the first path and a second filtered signal from the second path to generate the anti-noise signal. The first path includes a first digital filter adapted to operate at a filter frequency equal or greater than the microphone sampling frequency. The second path includes a second digital filter. The first digital filter may be a sigma-delta based filter that includes a sigma-delta modulator.
Claims22
An anti-noise signal generator comprising
- a first microphone input adapted to receive a first sigma-delta modulated signal at a microphone sampling frequency;
- and
- a combiner coupled to the first microphone input via a first path and a second path, the combiner being adapted to combine a first filtered signal from the first path and a second filtered signal from the second path to generate the anti-noise signal;
- wherein the first path comprises a first digital filter coupled to the first microphone input;
- the first digital filter being adapted to filter the first sigma-delta modulated signal and to operate at a filter frequency equal or greater than the microphone sampling frequency;
- and
- wherein the second path comprises a second digital filter adapted to filter the first sigma-delta modulated signal.
An audio device comprising
- a first microphone adapted to provide a first sigma-delta modulated signal at a microphone sampling frequency;
- an anti-noise signal generator for generating an anti-noise signal and
- a speaker for converting the anti-noise signal into a wave;
- the anti-noise signal generator comprising
- a first microphone input adapted to receive the first sigma-delta modulated signal from the first microphone;
- and
- a combiner coupled to the first microphone input via a first path and a second path, the combiner being adapted to combine a first filtered signal from the first path and a second filtered signals from the second path to generate the anti-noise signal;
- wherein the first path comprises a first digital filter coupled to the first microphone input;
- the first digital filter being adapted to filter the first sigma-delta modulated signal and to operate at a filter frequency equal or greater than the microphone sampling frequency and
- wherein the second path comprises a second digital filter adapted to filter the first sigma-delta modulated signal.
A method of generating an anti-noise signal, the method comprising
- converting a sound into a first sigma-delta modulated signal at a sampling frequency;
- filtering the first sigma-delta modulated signal along a first path to provide a first filtered signal;
- wherein the first path comprises a first digital filter adapted to filter the first sigma-delta modulated signal and to operate at a filter frequency equal or greater than the sampling frequency;
- filtering the first sigma-delta modulated signal along a second path to provide a second filtered signal;
- wherein the second path comprises a second digital filter adapted to filter the first sigma-delta modulated signal;
- combining the first filtered signal from the first path and a second filtered signals from the second path to generate the anti-noise signal.
Dependencies are inferred from the claim text.