Microphone assembly with pulse density modulated signal
First Claim
1. A microphone assembly comprising:
- a transducer configured to convert sound into an electrical signal; and
an electrical circuit comprising;
a multibit analog-to-digital converter coupled to an output of the transducer, the analog-to digital converter configured to receive, sample, and quantize the electrical signal to generate N-bit digital samples representative of the electrical signal;
a first digital-to-digital converter including a first quantizer and a first integrator coupled to an output of the first quantizer, wherein the first digital-to-digital converter is configured to quantize and noise-shape N-bit digital samples to generate a corresponding M-bit Pulse Density Modulated (PDM) signal based on a difference between the N-bit digital samples and a first feedback signal from the first integrator, wherein N and M are positive integers and N>
M;
a processor configured to control performance of the microphone assembly by configuring the first digital-to-digital converter with configuration information stored in a register of the electrical circuit;
a control interface over which configuration information in the register is to be written and read; and
a physical interface having contacts coupled to the electrical circuit.
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Abstract
The disclosure relates to a microphone assembly comprising a multibit analog-to-digital converter configured to receive, sample, and quantize a microphone signal to generate N-bit digital microphone samples representative of the microphone signal at a first sampling frequency. The microphone assembly also comprises a first digital-to-digital converter configured to receive, quantize, and noise-shape the N-bit digital microphone samples to generate a corresponding M-bit Pulse Density Modulated (PDM) signal, wherein N and M are positive integers, and N>M. The microphone assembly may comprise a SoundWire compliant data interface configured to repeatedly receive samples of the M-bit PDM signal and write bits of the M-bit PDM signal to a SoundWire data frame.
41 Citations
22 Claims
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1. A microphone assembly comprising:
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a transducer configured to convert sound into an electrical signal; and an electrical circuit comprising; a multibit analog-to-digital converter coupled to an output of the transducer, the analog-to digital converter configured to receive, sample, and quantize the electrical signal to generate N-bit digital samples representative of the electrical signal; a first digital-to-digital converter including a first quantizer and a first integrator coupled to an output of the first quantizer, wherein the first digital-to-digital converter is configured to quantize and noise-shape N-bit digital samples to generate a corresponding M-bit Pulse Density Modulated (PDM) signal based on a difference between the N-bit digital samples and a first feedback signal from the first integrator, wherein N and M are positive integers and N>
M;a processor configured to control performance of the microphone assembly by configuring the first digital-to-digital converter with configuration information stored in a register of the electrical circuit; a control interface over which configuration information in the register is to be written and read; and a physical interface having contacts coupled to the electrical circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An electrical circuit for a microphone assembly, the electrical circuit comprising:
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a multibit analog-to-digital converter configured to generate N-bit digital samples representative of an electrical signal, the electrical signal representative of acoustic activity detected by an electro-acoustic transducer; a first digital-to-digital converter including a first quantizer and a first noise-shaping integrator coupled to an output of the first quantizer, wherein the first digital-to-digital converter is configured to quantize and noise-shape N-bit digital samples to generate a corresponding M-bit Pulse Density Modulated (PDM) signal based on a difference between the N-bit digital samples and a first feedback signal from the first noise-shaping integrator, wherein N and M are positive integers and N>
M;a processor configured to configure the first digital-to-digital converter using configuration information stored in a register of the electrical circuit; and a control interface coupled to the register wherein configuration information is to be written to and read from the register via the control interface. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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17. A method in an acoustic microphone assembly comprising a transducer and an electrical circuit disposed in a housing having a physical interface, the method comprising:
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converting sound into an electrical signal using the transducer; generating N-bit digital samples representative of the electrical signal using an analog-to-digital converter of the electrical circuit; generating a M-bit Pulse Density Modulated (PDM) signal, where N and M are positive integers and N>
M, by quantizing and noise-shaping N-bit digital samples using a first digital-to-digital converter;controlling performance of the microphone assembly by configuring the first digital-to-digital converter with configuration information read from a register of the microphone assembly; and providing a PDM signal to the physical interface. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification