In the last few years, semiconductor manufacturing has become more prevalent and accessible, with MEMS (Microelectromechanical systems) technology now having advanced to a point that we can design speakers with characteristics that are fundamentally different from traditional dynamic drivers or balanced armature units.

Besides the simplification of the manufacturing line, another big advantage of the lithographic aspect of a MEMS speaker is the fact that its manufacturing precision and repeatability are significantly superior to that of a more variable voice coil design.

xMEMS’ Montara design comes in an 8.4 x 6.06 mm silicon die (50.9mm²) with 6 so-called speaker “cells” – the individual speaker MEMS elements that are repeated across the chip.

One key aspect of the capacitive piezo-drive is that it requires a different amplifier design to that of classical speaker.

As such, customers wishing to deploy a MEMS speaker design such as the Montara requires an additional companion chip, such as Texas Instruments’ LM48580.

In my view this is one of the big hurdles for more widespread adoption of the technology as it will limit its usage to more integrated solutions which do actually offer the proper amplifier design to drive the speakers – a lot of existing audio solutions out there will need an extra adapter/amp if any vendor actually decides to actually make a non-integrated “dumb” earphone design (As in, your classical 3.5mm ear/headphones).

TWS (True wireless stereo) headphones here obviously are the prime target market for the Montara as the amplifier aspect can be addressed at design, and such products can fully take advantage of the size, weight and power advantages of the new speaker technology.

In measurements, using the crude 3D-printed earphone prototype depicted earlier, xMEMS showcases that the Montara MEMS speaker has significantly higher SPL than any other earphone solution, with production models fully achieving the targeted 115dB SPL (The prototype only had 5 of the 6 cells active)