MEMS microphone to help voice recognition
Many of today's portable electronic devices are on the cusp of an audio revolution. While in recent years designers have focused on the development of exciting new functions, such as wireless Internet access and mobile TV reception, advancement of audio functions has lagged behind. Analog Devices, well known for delivering high-performance audio signal processing technology, has created two new MEMS microphones that enable advanced audio functions for portable electronics. These functions include high-fidelity audio/video playback, hands free communication, and voice recognition with built-in wind noise suppression, and TIA-920-compliance for VoIP applications.
The new ADMP404 and ADMP405 iMEMS microphones combine ADI's audio signal processing expertise with its innovative patented and patent-pending iMEMS technology. The resulting MEMS microphones offer the industry's highest SNR (signal-to-noise ratio) of 62 dB A-weighted and the highest PSRR (power supply rejection ratio) of 70 dBV with integrated high-pass filtering. End-product manufacturers can now develop portable electronic devices that deliver clearer, more intelligible voice quality without the background noise/hiss produced by other microphones with lower SNR. The ADMP404 and ADMP405 are available in a small and thin 3.35 mm × 2.50 mm × 0.88 mm surface-mount package that is reflow-solder-compatible with no sensitivity degradation. The ADMP404 and ADMP405 are halide-free.
Delivering a flat wideband frequency response from 100 Hz to 15 kHz on the ADMP404 and from 200 Hz to 15 kHz on the ADMP405, these new MEMS microphones eliminate the need for hardware filtering or advanced signal processing to enhance audio acquisition. The ADMP405 with a 200 Hz roll-off is the industry's first with this capability, enabling engineers to filter wind noise or fan noise energy at the transducer; this provides a clearer audio signal that can be more easily conditioned with any downstream signal processing. Engineers can now move beyond simple command and control voice recognition to full voice recognition for hands-free, translator, and dictation applications.
"There's a growing recognition by system designers that poor microphone performance at the front end significantly increases requirements for downstream audio processing. This leads to higher power consumption, higher cost and a more complex system design," said Mark Martin, vice president, MEMS/Sensor Group, Analog Devices. "By leveraging ADI's proven iMEMS® and audio signal processing technologies, these new MEMS microphones simplify designs and enable many new high performance capabilities for portable consumer and industrial products."
