1 / 13

Dual Coil Micro-Speaker

Dual Coil Micro-Speaker. EMCR870 MEMS Fabrication February 26 2007 Chris Nassar. Design. Two aluminum 38 turn square coils acting in parallel. Large low Resistance poly silicon return path 4440 µm X 4000 µm Diaphragm. MAGNET. Resistance Calculations.

neci
Download Presentation

Dual Coil Micro-Speaker

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dual Coil Micro-Speaker EMCR870 MEMS Fabrication February 26 2007 Chris Nassar

  2. Design • Two aluminum 38 turn square coils acting in parallel. • Large low Resistance poly silicon return path • 4440µm X 4000 µm Diaphragm MAGNET

  3. Resistance Calculations • Using this formula, the number of squares in the original design was 20256. • The inner 10 coils (1180 squares) were removed yielding a total of 19076 squares. • Using a sheet resistance of .028/sq for Al, the resistance of one coil is found to be 534. • The sheet resistance of the poly was 98/sq. The poly return path can be approximated to be slightly over a quarter of a square. • A poly resistance of 30 will be used in all further calculations.

  4. Simple Circuit Theory • The thevenin resistance of the complete circuit shown above is 290 using the values calculated on the previous page.

  5. Measured Resistance Metal 1: Average = 604, Stdev = 124 Metal 2: Average = 879, Stdev = 114

  6. Theoretical Displacement Force on one coil Circular diaphragm displacement E = Young’s Modulus,  = Poisson’s Ratio for Aluminum  =0.35 *The second equation corrects all units assuming that pressure is mmHg, radius and diaphragm is m, Young’s Modulus is dynes/cm2, and the calculated displacement found is m.

  7. Audio Amplifier Circuit • DC bias point must put the diaphragm on the edge of deflection and keep the power MOSFET in saturation. • The signal must be centered around the DC bias point. • It must provide some amplification

  8. Audio Amplifier Circuit • Approximate Voltage/Current Levels used • VDD ≈ 6V • Vgate≈ 3V • Id≈ .2A • Vhigh voltage supply≈ 70V

  9. Test Setup

  10. ResultsMicro-Speaker in action

  11. Frequency Analysis Micro-Speaker Queen’s original

  12. Frequency Analysis Micro-Speaker after noise removal and amplification Queen’s original

  13. Looking Ahead • Analysis of Frequency Response • Is the poor quality due to the electronics or the membrane? • Low voltage version • Integrated Electronics

More Related