poly seminar-mems microphone jmsheed

WELCOME…WELCOME… A SEMINAR ON

MEMS MICROPHONE

Jamsheed . p ES5

NO : 13

OUT LINE…OUT LINE… Introduction MEMS technology Microphone structure Microphone structure Working Performance parameters Applications Advantages Conclusion

INTRODUCTIONINTRODUCTION

MEMS technology provides a promising implementation for microphones.

Here, we discuss the design , characteristics & applications of MEMS microphone.

MEMS TECHNOLOGYMEMS TECHNOLOGY

MEMS is a process technology used to create tiny integrated devices or systems that combine mechanical and electrical components.

They are fabricated by integrated circuit (IC) batch processing techniques.

MEMS TECHNOLOGY …..MEMS TECHNOLOGY …..

Can range from a few micrometers to millimeters.

These devices have the ability to sense , control and actuate on the micro scale and generate effects on macro scales.

MICROPHONE STRUCTUREMICROPHONE STRUCTURE

MICROPHONE ARCHITECTUREMICROPHONE ARCHITECTURE

WORKING….WORKING….

WORKING…WORKING…

Transduction principle is the coupled capacity change between a fixed plate and a movable plate.

Change in air pressure created by sound waves cause the thin membrane to flex while the thicker back-plate remains stationery .

The movement of membrane creates a change in capacitance between the membrane and back plate, which is translated to an electrical signal by an interface IC.

Performance parameters…Performance parameters…Sensitivity

It is the measure of microphones response to a given sound.Sensitivity of microphone can be adjusted by changing the gain.Normally specified in dB FS (for digital mic) or dBV (for analog mic).Sensitivity of microphone sensor is an important factor in determining the SNR.Sensors with higher sensitivity increases the SNR.

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Performance parameters…Performance parameters… ( (cntd)cntd)

Noise floorIt is the measure of amount of noise created by

itself.The noise floor of the microphone is its output amplitude in the absence of sound.Normally specified in dB FS (for digital mic)

or dBV (for analog mic).


Signal to noise ratio It is defined as the difference between its sensitivity

and its noise floor.Sound pressure level

Sound pressure level is the logarithmic measure of change in air pressure caused by sound and specified in dB SPL .

Acoustic overload pointit is the maximum sound level that a microphone can faithfully capture.


Dynamic rangeThe dynamic range of microphone is the difference between its acoustic overload point and its noise floor . It is Measured in dB.

TYPES OF MEMS MICROPHONE …TYPES OF MEMS MICROPHONE …

Analog type: which converts sound input to corresponding voltage output

Digital type: Gives a digit output typically a pulse density modulation

APLLICATIONS…APLLICATIONS…

ADVANTAGES…ADVANTAGES… Can be manufactured using surface mount

technology Can withstand high temperature , vibrations Easily integrated with CMOS process Provides Improved noise cancellation Low power consumption High signal to noise ratio (70 dB) Very small size (1.05 mm)

CONCLUSIONCONCLUSION MEMS technology provides a promising

implementation for microphones.

MEMS microphone is an excellent choice for applications with size constraints.

References References S. D. Senturia, Microsystems Design. New York: Kluwer

Academic, 2001. V. P. Klimashin, “Mems technology,” Pribory i Tekhnika

Eksperimenta, Internet www.st.com/microelectronics

THANKS….THANKS….

poly seminar-mems microphone jmsheed

Technology