CMOS 3-axis accelerometers with integrated amplifier

Design, fabrication, and testing of multi-axis CMOS piezoresistive accelerometers is described. Vertical axis accelerometers have been fabricated in multiple processes using a production tested maskless bulk etch step. Horizontal axis accelerometers have also been fabricated and require an additional assembly step. Acceleration sensing in based on the piezoresistive behavior of the gate polysilicon in standard CMOS. Integrated amplifiers were designed and built on chip and have been characterized. Characterization is also presented for sensitivity, angular response, frequency response, axis of maximum sensitivity, temperature coefficient of offset, and temperature coefficient of sensitivity. Results are presented for a single chip with integrated full three axis acceleration sensing.

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