Microphones are a key component in any cell phone. But they’re also widely used in many other consumer products like laptops, tablets, cordless phones, headsets, game consoles, and video cameras. Up until recently, the most widely used microphone was the electret condenser microphone (ECM). This capacitive transducer uses a fixed plate, a moving plate, and a fixed charge dielectric.

But as microelectromechanical systems (MEMS) technology has improved, so have MEMS microphones, which now provide better voice quality. For example, Akustica’s AKU340 analog MEMS microphone uses a two-chip design with a MEMS capacitor sensor on one chip and an amplifier on the second chip (see the figure).

The combination is housed in a 3.35- by 2.5- by 1-mm metal package that’s designed for surface mounting. The AKU340 boasts a frequency range of 50 Hz to 20 kHz and sensitivity of –38 dB ±2, which is closely controlled to minimize the matching problem in two microphone noise cancelling devices. The signal-to-noise ratio is typically 63 dB. And, the AKU340 operates from 1.65 to 3.6 V range with a current draw of less than 300 µA.

Akustica, a division of Bosch, patented the first MEMS digital microphone. The company first introduced the AKU230, a CMOS device that’s widely used in laptops and tablets, in March 2011. The AKU340 suits smart phones, tablets, and especially devices with two or more microphones. Samples are available now with full production available in the third quarter of 2012. It costs $1.34 in 1000-unit quantities.

Akustica Inc.
www.akustica.com