Title :
Surface micromachined accelerometers
Author :
Boser, Bernhard E. ; Howe, Roger T.
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., California Univ., Berkeley, CA, USA
fDate :
3/1/1996 12:00:00 AM
Abstract :
Surface micromachining has enabled the cofabrication of thin-film micromechanical structures and CMOS or bipolar/MOS integrated circuits. Using linear, single-axis accelerometers as a motivating example, this paper discusses the fundamental mechanical as well as the electronic noise floors for representative capacitive position-sensing interface circuits. Operation in vacuum lowers the Brownian noise of a polysilicon accelerometer to below 1 μg/√(Hz). For improved sensor performance, the position of the microstructure should be controlled using electrostatic force-feedback. Both analog and digital closed-loop accelerometers are described and contrasted, with the latter using high-frequency voltage pulses to apply force quanta to the microstructure and achieve a very linear response
Keywords :
BiCMOS integrated circuits; CMOS integrated circuits; accelerometers; electric sensing devices; feedback; integrated circuit noise; integrated circuit technology; micromachining; microsensors; Brownian noise reduction; CMOS integrated circuits; HF voltage pulses; analog closed-loop accelerometers; bipolar/MOS integrated circuits; capacitive position-sensing interface circuits; cofabrication; digital closed-loop accelerometers; electronic noise; electrostatic force-feedback; linear response; linear single-axis accelerometers; polysilicon accelerometer; surface micromachined accelerometers; thin-film micromechanical structures; Accelerometers; Electrostatics; Force control; Integrated circuit noise; MOS integrated circuits; Mechanical sensors; Micromachining; Micromechanical devices; Microstructure; Thin film circuits;
Journal_Title :
Solid-State Circuits, IEEE Journal of
