Miniaturised Silicon Microphones with Integrated Signal Processing

INT. MIC - CP94-515

Keywords: microphones, signal processing, microsystems, hearing aid, acoustical metrology, DSP

Start Date: 1 April 95 / Duration: 24 months

[ participants / contact]

Objectivies and Approach

The objective of this project is to develop a miniaturised silicon condenser microphone with integrated signal preprocessing electronics and a matching processor for signal postprocessing. The microphone will be suitable for hearing aids, acoustical metrology, active noise control, safety systems, and commercial electronics and audio technologies.

Progress and Results

During the first year, the group in Furtwnagen fabricated the condensed microphone with a very small membrane area of only 500µ*500µ to 100µ*100µ as one electrode and a perforated polysilicon backplate as the other electrode. The single chip microphone design affords the simultaneous fabrication of the microphone and the signal preprocessing integrated circuits (CMOS-technology). Regarding the signal preprocessing element, a chip has been designed and processed externally by EUROPRACTICE by using a professional chip manufacturer. The test results were very promising.

The group in Budapest, which is also responsible for the postprocessing electronics, established an appropriate theory to find very low complexity DSP arithmetical blocks for the direct filtering of the modulated signals. The group in Prague delivered the acoustical theory to optimise the structure of the microphone, as well as the measurement-chamber. First measurements with this chamber are in progress.

Information Dissemination Activities and/or Exploitation

Results achieved so far have been published in international journals and presented at congresses. In addition, contacts are being sought amongst microphones manufacturers who can produce microphones in silicon technology.


Fachhochschule Furtwangen
Institut für Angewandte Forschung (IAF)
Gerwigstr. 11
D-78120 Furtwangen, D

EU Partners

Fachhochschule Furtwangen
Institut für Angewandte Forchung, D

Non-EU Partners

Kando Kalman College of Engineering, HU
Czech Technical University, Prague, CZ


Prof. Dr. Axel Stoffel
Tel: +49 7723 92 03 29
Fax: +49 7723 92 06 10

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INT. MIC - CP94-515, May 1997

please address enquiries to the ESPRIT Information Desk

html version of synopsis by Nick Cook