Why you need high performance, ultra-high SNR MEMS microphones
Best-in-class MEMS microphones
So far, the comparison has been with the conventional ECM and shows why MEMS microphone are replacing them in many applications and made possible new applications. So which model of MEMS microphone to choose? Infineon has been perfecting its MEMS microphones for over 15 years and offers the best-in-class solutions with its XENSIV™ products. For example, based on an internal study, a high SNR microphone results in up to 40% better performance than its nearest, competitive, standard SNR MEMS microphone for word recognition and capture at low input sounds such as whispers. This high SNR also means that it is up to 25% better than competitors in a ‘cross room scenario’ where the speaker is across a room or even in a next-door room making it the ideal choice for integrating voice controls into almost any smart home device.
Download PDF Brochure of study, Click Here!
What are MEMS Microphones and how do they work?
MEMS microphones, also known as a microphone chip, is a miniature SMT acoustic device that picks up sound waves. It typically consists of two parts situated side by side; the ASIC chip and the MEMS acoustic sensor mounted on a PCB board, which is then enclosed within a metal or plastic casing. Sound waves must enter the enclosure to reach the acoustic sensor somehow, so inevitably a physical hole is needed somewhere on the package. This hole or sound port can be located on the top of the package on the enclosure, or on the bottom. If it is located on the bottom, a hole needs to be drilled into the main PCB board as well.
With these basic considerations out of the way, designers can then evaluate the performance characteristics of individual microphones to make a final selection. The key parameters for a representative selection of available MEMS microphones are listed in a spreadsheet, downloadable by registered EP readers. Some of these specifications include:
- Port sensitivity — the output signal magnitude given a reference 94-dB -SPL acoustic signal at the port. This helps indicate the softest sounds that the microphone will pick up.
- SNR — the difference (in dB) between the microphone’s noise floor and the signal produced by a 94-dB, 1-kHz sound wave.
- Dynamic range — the spread of sound intensity levels that the microphone can reliably capture without distortion. It is essentially the difference (in dB) between the microphone’s noise floor and its AOP.
- Frequency range — the audio frequency range to which the microphone can respond without loss of sensitivity.