Capacitive sensors are replacing pendulous crystals in MEMS accelerometers.
Hitherto, modern small inertial navigators have used quartz micro-electromechanical system (MEMS) accelerometers, with a typical area of 8.8 x 7.0 mm. But new accelerometers are using capacitive sensors to measure acceleration in similar size packages.
A typical example is Silicon Designs’ Model 2227 module - claiming to be best-in-class as a low-mass, low-power module, electrically and mechanically compatible with, and designed to replace and upgrade, industry-standard quartz accelerometers.
The MEMS accelerometer combines 2 capacitive silicon sense elements and a complementary metal oxide semiconductor (CMOS) integrated circuit in the hermetically sealed package. The differential output voltage of the accelerometer is converted on the PCB into a current proportional to the detected acceleration.
These devices have detection ranges of +/-10, +/-25 or +/-50G and can withstand a shock of 5,000G. Weight of the chip is 5.6g.
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