Acoustic transducer and interface circuit

• US 9,380,380 B2
• Filed: 07/05/2013
• Issued: 06/28/2016
• Est. Priority Date: 01/07/2011
• Status: Active Grant

• Current Assignee: Omron Corporation, STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: Omron Corporation, STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Kasai, Takashi, Sato, Shobu, Uchida, Yuki, Padovani, Igino, David, Filippo, Conti, Sebastiano, Zerbini, Martino, Molinari, Luca
• Primary Examiner(s): Chin, Vivian
• Assistant Examiner(s): HAMID, AMMAR T
• Application Number:
  US13/936,110
• Publication Number:
  US 20140010374A1
• Time in Patent Office: 1,089 Days
• Field of Search: 381/56, 381/57, 381/122, 381/119, 381/26
• US Class Current: 1/1
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2924/16152 Cap comprising a cavity for hosting the device, e.g. U-shaped cap
• CPC Class Codes: H04R 1/086 Protective screens, e.g. all weather or wind screens
• CPC Class Codes: H04R 19/005 using semiconductor materials
• CPC Class Codes: H04R 19/016 for microphones
• CPC Class Codes: H04R 3/00 Circuits for transducers , loudspeakers or microphones
• CPC Class Codes: H04R 31/00 Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor manufacture of microstructural arrangements of deformable or non-deformable structures in general B81C1/00182

Abstract

The present disclosure is directed to an acoustic transducer configured to detect a sound wave according to changes in capacitances between a vibrating electrode and a fixed electrode. At least one of the vibrating electrode and the fixed electrode being divided into a plurality of divided electrodes, and the plurality of divided electrodes outputting electrical signals. The disclosure includes a digital interface circuit coupled to the divided electrodes. The circuit includes a recombination stage, which supplies a mixed signal by combining the first digital processed signal and the second digital processed signal with a respective weight that is a function of a first level value of the first processed signal. An output stage is included, which supplies, selectively and alternatively, a first processed signal, a second processed signal, or a mixed signal.

Claims

1. A device, comprising:

an acoustic transducer that includes;

a substrate;

a movable electrode, provided above the substrate; and

a fixed electrode provided above the substrate, the fixed electrode being configured to form a capacitor with the moveable electrode and to detect a sound wave, at least one of the moveable electrode and the fixed electrode being divided into a plurality of divided electrodes, the acoustic transducer being configured to convert the sound wave into a first electrical signal and a second electrical signal and output the first and second electrical signals; and

a mixing module configured to receive the first electrical signal and the second electrical signal and to output a mixed signal;

a low pass filter configured to receive the first electrical signal and configured to provide a filtered first electrical signal;

a first level measurement module configured to receive the filtered first electrical signal and to provide an output mode selection signal;

a second level measurement module configured to receive the filtered first electrical signal and to provide a weighted value to the mixing module; and

an output module configured to output the first electrical signal, the second electrical signal, or the mixed signal in response to the output mode selection signal.

2. The device of claim 1 wherein the first level measurement module includes a peak detection module configured to receive the filtered first electrical signal and output the output mode selection signal.

3. The device of claim 2 wherein the first level measurement module includes a selector module configured to compare the selection signal to a first threshold and a second threshold.

4. A device, comprising:

a substrate having an opening that is configured to receive a sound wave;

a first electrode provided adjacent to the opening in the substrate, the first electrode having a main movable portion and a side movable portion that is smaller than the main movable portion, the side movable portion extending from one side of the main movable portion;

a second electrode provided adjacent to the first electrode, at least one of the first electrode and the second electrode being divided into a plurality of divided electrodes, the plurality of divided electrodes being configured to output electrical signals based on changes in capacitances between the first electrode and the second electrode in response to the sound wave; and

an interface circuit configured to receive the electrical signals and configured to output one of the electrical signals or a mixed signal based on the electrical signals, the interface circuit including;

a mixing module configured to receive a first one of the electrical signals and a second one of the electrical signals and to output the mixed signal;

a low pass filter configured to receive the first one of the electrical signals and configured to provide a filtered first electrical signal;

a first level measurement module configured to receive the filtered first electrical signal and to provide an output mode selection signal;

a second level measurement module configured to receive the filtered first electrical signal and to provide a weighted value to the mixing module; and

an output module configured to output the first one of the electrical signals, the second one of the electrical signals, or the mixed signal in response to the output mode selection signal.

5. The device of claim 4 wherein the first level measurement module includes a selector configured to compare the first filtered electrical signal to threshold values.

6. The device of claim 5 wherein the selector is configured to generate the selection signal to select one of the electrical signals or the mixed signal.

7. An acoustic transducer system, comprising:

a first detection structure and a second detection structure, which are separate and distinct from one another and have different characteristics of detection of acoustic-pressure waves,

the first detection structure including;

a first part of a first electrode; and

a second electrode;

the second detection structure including;

a second part of the first electrode; and

the second electrode;

a digital interface circuit, coupled to the first detection structure and second detection structure, the digital interface circuit including;

first and second inputs configured to receive first and second detection signals, respectively, from the first and second detection structures, respectively;

a first digital processing path and a second digital processing path, which are coupled to the first input and the second input, respectively, and are configured to supply a first digital processed signal and a second digital processed signal, respectively;

a recombination stage configured to supply a mixed signal, via combination of the first processed signal and second processed signal with a respective weight in response to a first level value of the first processed signal; and

an output stage configured to selectively supply at an output alternatively the first digital processed signal, the second digital processed signal, and the mixed signal in response to a second level value of the first processed signal.

8. The system of claim 7, further comprising:

an ASIC circuit, electrically coupled to the first detection structure and the second detection structure;

wherein the digital interface circuit and the ASIC circuit are integrated in one and the same chip.

9. The system of claim 7, further comprising:

an ASIC circuit, electrically coupled to the first detection structure and the second detection structure and configured to receive and process respective electrical signals and generate an interlaced detection signal including information associated with both of the electrical signals;

the system including a sampling stage configured to receive the interlaced detection signal and configured to generate the first detection signal and the second detection signal for the digital interface circuit, each associated to a respective one of the first detection structure and the second detection structure.

10. The system of claim 7 wherein the first part of the first electrode is larger than the second part of the first electrode.

11. The system of claim 10 wherein the first part of the first electrode is rectangular and the second part of the first electrode is rectangular.

12. The system of claim 10 wherein the first part is partially separated from the second part by a thin, elongated opening.

13. The system of claim 10 wherein the first part is completely separated from the second part by a thin, elongated opening.

14. The system of claim 7 wherein the second electrode includes a first part and a second part that is separated from the first part by a dielectric.

15. The system of claim 14, further comprising a substrate, the second electrode being fixed with respect to the substrate.

16. A device, comprising:

a first membrane having a first moveable portion and a second moveable portion;

a second membrane configured to interact with the first membrane;

an audio signal processing circuit configured to receive a first audio signal and a second audio signal from the first moveable portion and the second moveable portion, respectively, the circuit including;

a first processing path configured to process the first audio signal and configured to generate a first processed signal;

a second processing path configured to process the first audio signal and configured to generate a second processed signal;

a recombination stage configured to receive the first processed signal and the second processed signal and configured to generate a mixed signal, the recombination stage including;

a first measurement module configured to receive the first processed signal and configured to generate a first measured signal;

a mixing module configured to receive the first measured signal, the second processed signal, the upper threshold value, and the lower threshold value, and configured to generate the mixed signal;

a selection stage configured to generate a selection signal based on a comparison of the first processed signal with an upper threshold value and a lower threshold value; and

a multiplexor configured to output one of the first processed signal, the second processed signal, the mixed signal based on the selection signal;

a second measurement module configured to receive the first processed signal and configured to generate a peak signal, the selection stage configured to receive the peak signal.

17. The device of claim 16 wherein the second measurement module is configured to identify a peak of the first processed signal and is configured to generate the peak signal based on the peak.