Electronic Design

MEMS Microphone-Amp Chip Breaks Acoustics Ground

Designed for hearing aids and cell-phone microphones, this advanced-design IC portends "killer" applications.

A combination MEMS microphone/amplifier chip holds the promise of generating large-scale applications for hearing aids and cell phones. According to Akustica's CEO and CTO, Kaigham (Ken) Gabriel, the company believes its new chip will make a major impact in applications where space constraints and performance demands are critical, due to its relatively low cost.

The analog chip is a multimembrane CMOS IC that holds an array of 64 micromachined condenser microphones etched in silicon. Also incorporated on the 3- by 3.65- by 0.5-mm chip is a MOSFET amplifier.

The chip's omnidirectional performance characteristics include a sensitivity (at 1 V/Pa) of -40 to +4 dB and a target noise level of 35 dB SPL (sound pressure level). Frequency range is 100 Hz to 10,000 kHz. The device typically operates from a 3-V supply (5 V maximum) and consumes less than a mere 130 µA. This level of performance requires much larger chips of electret microphones than those being used in hearing aids today.

The chip accepts a maximum input sound level of 110 dB and produces an analog output voltage. Future versions might also integrate analog-to-digital converters (ADCs) for digital outputs, providing even higher levels of noise immunity.

While the chip's exact price has yet to be set, Akustica believes it will fall between $1 and $7 for OEM quantities. Sample quantities will be available this summer.

See associated figure

Akustica Inc.
www.akustica.com
(412) 390-1730

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