Analog Devices is one chip supplier which believes the time has come for the MEMS microphone to match the cost and useability of traditional electret condenser microphones (ECMs) in volume consumer applications like mobile phones.

According to Todd Borkowski, MEMS marketing manager at Analog Devices, there are three factors which will drive the more sophisticated and higher-cost technology.

"Potential for higher audio quality, the small size and the presence in the market of multiple suppliers will affect the take-up of MEMS microphones," said Borkowski.

The traditional ECM can be used in high quality audio microphones, but MEMS suppliers argue that, while the MEMS technology is inherently lower noise and wider range, for ECMs this requires additional components and circuit design which drives up cost.

ADI’s first MEMS microphone has a signal-to-noise ratio of greater than 61dB, measured across the wider A-weighted audio frequency range.

The ADMP421 device is an omni-directional input microphone with a flat frequency response from 100Hz to 15kHz. It has digital or analogue outputs and delivers power supply rejection ratio of better than 50dBV on the analogue output.

The MEMS microphone with pulse density modulated digital output is designed for multimedia and VoIP-enabled cell phones and Bluetooth headsets. The digital output  provides high immunity to coupled noise from RF (radio frequency) and EMI (electromagnetic interference) emanating from sources such as WiFi antennas and LCD (liquid crystal displays) clock signals.

"By eliminating the need for analog signal conditioning, as well as the cable shielding materials commonly required to route analog signals, system designers can optimise the placement of the ADMP421 digital MEMS microphone to improve audio-enhancement features, such as stereo sound and array beam forming," said the supplier.

The microphone features 80dBFS PSRR (power supply rejection ratio), Left/Right select, and integrated sleep mode.

ADI joins suppliers such as US-based Akoustica. Panasonic and Infineon Technologies in the market.

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