A differential capacitive low-g microaccelerometer with m g resolution

A low-cost differential capacitive accelerometer with a resolution of 5 mg (1 g = 9.81 m/s(2)) and high sensitivity (800 mV/g) has been designed with a full measurement range of +/- 2g. By using the single crystal reactive io n etching and metallisation (SCREAM) process, beams with high aspect ratio, small air gap for large capacitance variation and low parasitic capacitanc e have been attained. The fabricated microaccelerometer also offers high ou tput and it has successfully survived a shock of 1000 g. The effects of ele ctrostatic spring constant on the natural frequency and sensitivity of the accelerometer have been thoroughly discussed, and obliqueness of the beams has also been taken into consideration. The ratiometric error has been stud ied, and is well below 2% with a cross axis sensitivity of less than 3%. Th e operating voltage is 5 V DC. The construction is based on a two-chip desi gn and the sensing element is connected to a CMOS ASIC by wire bonding. (C) 2000 Elsevier Science B.V. All rights reserved.