The technology behind
Optical MEMS microphone technology
A quantum leap in audio capture
Capture audio with ultra-low noise and handle high sound levels with ease.
An optical MEMS microphone measures the movement of its diaphragm with light instead of capacitance. sensiBel’s microphones use a VCSEL laser, a diffractive optical element and a photodetector to read the diaphragm. This removes the backplate that limits conventional MEMS microphones, and gives the SBM140B 84 dBA SNR, 10 dBA SPL self-noise, a 146 dB SPL acoustic overload point and 136 dB dynamic range in a 6 × 3.8 mm package.
How an optical MEMS microphone works
Sound pressure moves the MEMS diaphragm.
A VCSEL laser and a photodetector, together with a diffractive optical element, measure the diaphragm’s displacement optically.
The ASIC converts the signal to 24-bit digital audio over PDM, I²S or 8-channel TDM.
![SBM100B component: metal lid of the bottom-port MEMS package [CHECK ORDER]](https://framerusercontent.com/images/lwSySSoxHSg4KrSxoMGwzNkEpBs.png?width=1440&height=796)
![SBM100B component: optical detection module with VCSEL laser, photodetector and diffractive optical element [CHECK ORDER]](https://framerusercontent.com/images/EZL23vLwCfuafrMp34QoivUJtbk.png?width=1440&height=796)
![SBM100B component: MEMS diaphragm and ASIC [CHECK ORDER]](https://framerusercontent.com/images/fBI6V85NUS3R1psFe2e9eakbEJY.png?width=1440&height=796)
![Assembled SBM100B optical MEMS microphone package [CHECK ORDER]](https://framerusercontent.com/images/oofLFEKghO9ow1YsxeqENxX3ms.png?width=1440&height=796)
Conventional MEMS microphone packaging
The SBM100B package consists of a bottom substrate and top metal lid; the industry standard for bottom-port MEMS microphones, and is surface mount (SMT) reflow compatible.
Improved MEMS detection system
The advantage of
Optical MEMS microphones
Capacitive MEMS
sensiBel
136 dB DNR
Wide dynamic range
The sensiBel optical MEMS microphone with digital output provides a dynamic range of up to 136dB. Where other MEMS microphones are typically limited to dynamic range below 110dB, the sensiBel microphone is comparable to some of the best studio microphones, making this level of performance affordable in volume applications. The SBM100B dynamic range performance means that very low noise levels and very high sound levels can be captured using a single microphone. This dynamic range is supported by the SBM140B’s 24-bit digital output.
84 db SNR
Low Noise - High SNR
sensiBel reaches incredibly low noise and high Signal to Noise Ratio (SNR) levels, with 84dBA (EIN of 10dBA SPL). This SNR of 84dBA is almost 14dB higher than other digital MEMS microphones available today, meaning crystal clear recordings. This performance is important in applications where audio fidelity is critical, like studio recordings and applications where distant sounds can otherwise get lost in the self-noise of the microphone. In applications where advanced processing of microphone signals is carried out, such as microphone array beamforming or active noise cancellation, very high SNR reduces white noise gain to create a more optimised signal.
146 dB AOP SPL
High overload point - Low distortion
The sensiBel microphones can be used everywhere - even the loudest environments - meaning sound can be captured with very low distortion due to the microphones very high AOP (Acoustic Overload Point). SBM100B and SBM140B has an AOP of up to 146dB SPL, over 10dB higher than leading MEMS microphones available today. The ability to handle high sound pressure levels without sacrificing audio fidelity ensures that the true dynamics and detail of a sound event, such as a live music performance, are captured cleanly and accurately. Very high AOP is also an important advantage for industrial applications such as machine health monitoring where intensely loud sounds can be a common occurrence.