STMicroelectronics, a leading supplier of MEMS devices for consumer and portable applications, introduced this week two new digital MEMS microphones for mobile phone and portable computer applications. According to IHS iSuppli, the market for MEMS microphones for consumer electronics and mobile handsets is forecast to grow revenue at an annual rate of 24% between 2009 and 2014. The driving factors include the breakthrough in the use of noise suppression requiring multiple microphones, as well as adoption in new consumer applications beyond handsets and laptops, such as slate tablets and gaming.
ST's MEMS microphones use the company's acoustic sensor technology, jointly developed with OMRON, that is "inherently less susceptible" to mechanical vibration, temperature variations and electromagnetic interference, while providing high-fidelity reproduction of audio signals. The new products are made by integrating ST's electronic control circuit and OMRON's micro-machined sensor in a single package.
In addition to the size, robustness and energy economy advantages over the traditional ECM microphones, MEMS microphones can also enable improvements in sound quality, realized by incorporating multiple microphones in one device. Such microphone arrays, facilitated by the small form factor, enable the implementation of active noise and echo cancelling, as well as beam-forming, a sound-processing technology that helps isolate a sound and its location. These features are valuable with the increasing use of cell phones and other devices in noisy and uncontrollable environments.
Another important factor in multiple-microphone applications is the high temperature stability of MEMS microphones after reflow that ensures ample flexibility in placing the auxiliary microphones, including in locations with higher temperature excursions.
One of ST's new MEMS microphones are housed inside a 3x4x1 mm package which, according to the company, has been specifically designed for mobile phones, with the acoustic port hole placed on the bottom of the package. This layout apparantly enables phone manufacturers to mount the microphone on the backside of the cell-phone printed circuit board for slimmer designs and still obtain a short acoustic path from the environment to the microphone. ST says that this new microphone has already been qualified by top-tier cell-phone makers and is now in mass production.
The other ST MEMS microphone, is a top-port 3.76 x 4.72 x 1.25mm device that, accordingl to the company, ideally suits the size and sound-inlet position requirements of laptops and tablets.
ST's bottom-port MEMS microphone is available for volume shipping and the top-port microphone will start mass production in Q2 2011. Unit pricing for both devices is $1.4 in quantities of 1000 pieces. ST also offers audio processing chips that feature a dedicated built-in interface for direct connection of a MEMS microphone, saving parts count and cost.
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