A
new MEMS-based microphone offers better sound quality, greater range and
smaller size for VoIP-enabled cell phones, Bluetooth headsets and other
applications that rely on digitized sound.
Known as the ADMP421, the new microphone measures a scant 1
mm think, thanks to its use of microelectromechanical systems (MEMS)
technology. It also offers a flat frequency response to 15 kHz and a better
signal-to-noise ratio than previous microphones. Analog Devices (ADI), maker of
the microphone, says it is targeting the product toward the cell phone market,
among others.
"Having a smaller and more efficient microphone allows
manufacturers to build a better phone," notes Todd Borkowski, marketing manager
for ADI.
ADI engineers believe that the new microphone is entering the
market at the right time, especially since standards are changing to
accommodate wideband telephony. "The old telephony standard only went to 3
kHz," says Alex Ahenkin, senior acoustics engineer for ADI. "But now that that
the standard extends to 8 kHz, many of the older microphones won't have the
frequency response to accommodate the higher bandwidth."
Along with the ADMP421's 15-kHz frequency response, ADI says
it also delivers the industry's highest signal-to-noise ratio. The 61-dB
signal-to-noise ratio is reportedly about 6 dB better than predecessors.
"That represents an effective doubling of the distance that
the microphone can be used at," Ahenkin says.
As a result, the microphone offers an advantage in hands-free
phones, which often must pick up sounds at a distance of several feet. It also
could help in next-generation cell phones that incorporate video. ADI engineers
say that until now phone-based video typically has suffered from lack of
quality audio, but the new system could help because it provides quality audio
at a size that's small enough for use in cell phones.
"The emphasis today is on thinness," Borkowski says.
"In a densely packaged cell phone, every millimeter makes a huge difference to
the cell phone manufacturer."
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