Abstract

A microelectromechanical-systems (MEMS)-based electromagnetically actuated loudspeaker to reduce form factor, cost, and power consumption, and increase energy efficiency in hearing-aid applications is presented. The MEMS loudspeaker has multilayer copper coils, an NiFe soft magnet on a thin polyimide diaphragm, and an NdFeB permanent magnet on the perimeter. The coil impedance is measured at 1.5Ω , and the resonant frequency of the diaphragm is located far from the audio frequency range. The device is driven by a power-scalable, 0.25-μm complementary metal-oxide semiconductor class-D Σ △ amplifier stage. The class-D amplifier is formed by a differential H-bridge driven by a single bit, pulse-density-modulated Σ △ bitstream at a 1.2-MHz clock rate. The fabricated MEMS loudspeaker generates more than 0.8-μm displacement, equivalent to 106-dB sound pressure level (SPL), with 0.13-mW power consumption. Driven by the Σ △ class-D amplifier, the MEMS loudspeaker achieves measured 65-dB total harmonic distortion (THD) with a measurement uncertainty of less than 10%. Energy-efficient and cost-effective advanced hearing aids would benefit from further miniaturization via MEMS technology. The results from this study appear very promising for developing a compact, mass-producible, low-power loudspeaker with sufficient sound generation for hearing-aid applications. Copyright copy; 2009 IEEE.

Original languageEnglish (US)
Pages (from-to)348-358
Number of pages11
JournalIEEE Transactions on Biomedical Circuits and Systems
Volume3
Issue number5
DOIs
StatePublished - Oct 2009

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Hearing aids
Loudspeakers
MEMS
Costs
Diaphragms
Electric power utilization
Acoustic waves
Acoustic impedance
Harmonic distortion
Polyimides
Permanent magnets
Magnets
Energy efficiency
Clocks
Natural frequencies
Multilayers
Copper
Metals

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Biomedical Engineering

Cite this

A compact and low-cost MEMS loudspeaker for digital hearing aids. / Je, Sang Soo; Rivas, Fernando; Diaz, Rodolfo; Kwon, Jiuk; Kim, Jeonghwan; Bakkaloglu, Bertan; Kiaei, Sayfe; Fellow, ; Chae, Junseok.

In: IEEE Transactions on Biomedical Circuits and Systems, Vol. 3, No. 5, 10.2009, p. 348-358.

Research output: Contribution to journalArticle

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