DIGITAL MICROPHONE NOISE ATTENUATION
First Claim
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1. A system comprising:
- a first microphone assembly comprising a first microelectromechanical systems (MEMS) transducer and a first integrated circuit, the first integrated circuit configured to;
convert a first analog signal produced by the first MEMS transducer to a first digital signal;
convert the first digital signal to a first pulse density modulated (PDM) signal to generate a first digital microphone output signal; and
provide the first digital microphone output signal on a common interface; and
a second microphone assembly comprising a second MEMS transducer and a second integrated circuit, the second integrated circuit configured to;
convert a second analog signal produced by the second MEMS transducer to a second digital signal;
remove a direct current (DC) signal component from the second digital signal;
apply a DC offset to the second digital signal to affect an idle tone frequency of the second digital signal;
convert the second digital signal to a second PDM signal to generate a second digital microphone output signal; and
provide the second digital microphone output signal on the common interface.
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Abstract
A digital microphone device includes circuitry that can reduce the risk of noise caused due to an idle tone frequency component in a digital signal output by the digital microphone device. In stereo mode and other applications where interference occurs between two or more such microphones, each microphone device includes a digital output having a corresponding idle tone frequency, one of which is offset to shift noise components outside of a desired frequency range.
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Citations
20 Claims
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1. A system comprising:
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a first microphone assembly comprising a first microelectromechanical systems (MEMS) transducer and a first integrated circuit, the first integrated circuit configured to; convert a first analog signal produced by the first MEMS transducer to a first digital signal; convert the first digital signal to a first pulse density modulated (PDM) signal to generate a first digital microphone output signal; and provide the first digital microphone output signal on a common interface; and a second microphone assembly comprising a second MEMS transducer and a second integrated circuit, the second integrated circuit configured to; convert a second analog signal produced by the second MEMS transducer to a second digital signal; remove a direct current (DC) signal component from the second digital signal; apply a DC offset to the second digital signal to affect an idle tone frequency of the second digital signal; convert the second digital signal to a second PDM signal to generate a second digital microphone output signal; and provide the second digital microphone output signal on the common interface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A microphone assembly comprising:
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a micro electromechanical systems (MEMS) transducer configured to generate an analog signal responsive to an acoustic signal; and an integrated circuit coupled to the MEMS transducer and configured to; convert the analog signal to a digital signal; remove a direct current (DC) signal component from the digital signal; apply a DC offset to the digital signal to affect an idle tone frequency of the digital signal; convert the digital signal to a PDM signal to generate a digital microphone output signal. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A method in a microphone assembly comprising a microelectromechanical systems (MEMS) transducer and an integrated circuit, the method comprising:
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converting an analog signal produced by the MEMS transducer to a digital signal; removing a direct current (DC) signal component from the digital signal; applying a DC offset to the digital signal to affect an idle tone frequency of the digital signal; and converting the digital signal to a pulse density modulated (PDM) signal after applying the DC offset to the digital signal to generate a digital microphone output signal. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification