阅读说明：本技术 Mems麦克风 (MEMS microphone ) 是由 D·斯特雷尤斯尼格 B·塞特尔 于 2019-05-21 设计创作，主要内容包括：实施例提供了一种MEMS麦克风,其包括MEMS麦克风单元和连接在MEMS麦克风单元下游的调制器。调制器被配置为向待调制的信号施加定义的相移。(Embodiments provide a MEMS microphone comprising a MEMS microphone unit and a modulator connected downstream of the MEMS microphone unit. The modulator is configured to apply a defined phase shift to the signal to be modulated.)

1. A MEMS microphone (102), comprising:

A MEMS microphone unit (104), and

A modulator (110) connected downstream of the MEMS microphone unit (104),

Wherein the modulator (110) is configured to apply a defined phase shift to the signal (120) to be modulated.

2. The MEMS microphone (102) of the preceding claim,

wherein the modulator (110) is configured to apply the defined phase shift to the signal to be modulated (120) in order to reduce a limit period of the modulator.

3. MEMS microphone (102) according to one of the preceding claims,

wherein the modulator (110) is configured to apply an adjustable phase shift to the signal (120) to be modulated.

4. MEMS microphone (102) according to one of the preceding claims,

wherein the modulator (110) is configured to adjust the phase shift in dependence on a level of the signal (120) to be modulated.

5. MEMS microphone (102) according to one of the preceding claims,

Wherein the modulator (110) is configured to apply a delay to the signal to be modulated (120) as the phase shift.

6. MEMS microphone (102) according to one of the preceding claims,

Wherein the delay is equal to a sampling period of the signal to be modulated or a fraction or a multiple of the sampling period.

7. MEMS microphone (102) according to one of the preceding claims,

Wherein the modulator (110) is a digital modulator.

8. MEMS microphone (102) according to one of the preceding claims,

Wherein the modulator (110) is a sigma-delta analog-to-digital converter.

9. MEMS microphone (102) according to one of the preceding claims,

Wherein the modulator (110) is a single bit modulator.

10. MEMS microphone (102) according to one of the preceding claims,

Wherein the modulator (110) comprises a phase shifter (124) configured to apply the defined phase shift to the signal to be modulated (120).

11. MEMS microphone (102) according to one of the preceding claims,

Wherein the modulator (110) comprises a quantizer (126) connected downstream of the phase shifter (124).

12. a MEMS microphone module (100) comprising:

The first MEMS microphone (102_1) of any one of the preceding claims, and

A second MEMS microphone (102_2) according to any of the preceding claims.

13. the MEMS microphone module (100) of the preceding claim,

wherein the modulators (110_1, 110_2) of the first and second MEMS microphones (102_1, 102_2) are configured to apply different phase shifts to the signal to be modulated.

14. A method (200) for operating a MEMS microphone (102), the MEMS microphone (102) comprising a MEMS microphone unit (104) and a modulator (110) connected downstream of the MEMS microphone unit (104), wherein the method (200) comprises:

Applying (202) a defined phase shift to the signal (120) to be modulated by the modulator (110).

15. A computer program for performing the method according to the preceding claim when run on a computer or microprocessor.

Technical Field

Background

When using certain input signals (e.g., constant input signals), undesirable tones (limited periods) occur in sigma-delta ADCs and digital modulators. For example, tones may appear in the useful band, which is particularly problematic (audible) in audio applications. On the other hand, especially when using a single-bit modulator, strong confinement periods occur around Fs/2.

The limiting period causes interference effects (stereo noise) in the useful frequency band, for example in stereo microphone applications. The interference component may also appear in the useful band due to the inter-modulation of the limit period of about half the sampling rate Fs/2 and interference to the reference.

a common method of minimizing the limit period is to add a so-called dither signal (pseudo-random signal). This signal is typically fed in front of the quantizer. The disadvantage of this approach is that it reduces the SNR (an unacceptably high level would have to be used for the dither signal in order to minimize the limit period of about half the sampling rate Fs/2, especially when using a single-bit modulator).

Disclosure of Invention

Drawings

Embodiments are described herein with reference to the drawings.

Fig. 1 shows a schematic block diagram of a MEMS microphone module comprising a first MEMS microphone and a second MEMS microphone;

FIG. 2 shows a schematic block diagram of a digital MEMS microphone;

FIG. 3 shows a schematic block diagram of a MEMS microphone in accordance with an embodiment;

FIG. 4 shows a schematic block diagram of a modulator according to an embodiment;

Fig. 5 shows a schematic block diagram of a modulator according to a detailed embodiment;

FIG. 6 shows a schematic block diagram of a digital stereo MEMS microphone module in accordance with one embodiment;

FIG. 7 graphically illustrates stereo noise (stereo) of the MEMS microphone module of FIG. 1 plotted in frequency, with the modulators without phase shifters, and noise (mono) of the modulators showing a single MEMS microphone plotted in frequency for comparison;

FIG. 8 graphically illustrates stereo noise (stereo) of the MEMS microphone module of FIG. 6 plotted in frequency with the modulator having a phase shifter and noise (mono) of the modulator showing a single MEMS microphone plotted in frequency for comparison;

FIG. 9 graphically illustrates the apparent limit period at half Fs/2 of the sampling frequency when using a modulator without a phase shifter;

FIG. 10 graphically illustrates a greatly reduced confinement period when using a modulator with a phase shifter; and

fig. 11 shows a flow diagram of a method for operating a MEMS microphone according to one embodiment.

Embodiments relate to MEMS microphones. Other embodiments relate to methods for operating a MEMS microphone. Other embodiments relate to a MEMS microphone module comprising two MEMS microphones. Some embodiments relate to idle tone reduction using phase shifters.