Steven J. Sherman

Single-chip surface micromachined integrated gyroscope with 50/spl deg//h Allan deviation

The design principles of a mass-produced surface micromachined gyroscope are described. The device is integrated on a single 3 mm/spl times/3 mm chip with a 3-/spl mu/m BiCMOS process. It has a 4-/spl mu/m-thick polysilicon structure, 5-V 6-mA supply, 12.5-mV//spl deg//S sensitivity, 10 000:1 dynamic range, 30 000-gee shock survival, and -55/spl deg/C to +85/spl deg/C operating temperature.

A low cost monolithic accelerometer

The ADXL50, a complete scaled and temperature-compensated surface micromachined accelerometer with an output voltage proportional to acceleration with full-scale measurement range of +or-50 g and unpowered shock survival at 2000 g, is designed for crash detection in second-generation automotive air bag systems. A digitally activated self-test electrostatically deflects a functional beam so that a -50-g acceleration is indicated. An uncommitted amplifier, with rail-to-rail output range, allows rescaling and offsetting of the raw output signal. Capacitors can be introduced in the gain network surrounding the uncommitted amplifier so that two poles of low-pass filters are possible without the addition of off-chip active circuitry. Measured performance results for the ADXL50 are summarized.<<ETX>>

Surface micromachining: from vision to reality to vision [accelerometer]

Airbag deployment systems demand reliable, inexpensive sensing of deceleration of the car during collision. The integrated accelerometer combines a 0.3 mm/sup 2/ micromechanical capacitive sensing element with precision bipolar/MOS control circuitry in a 9 mm/sup 2/ area. The microstructure is fabricated from a layer of deposited polysilicon by surface micromachining. This chip is an A/V (acceleration-to-voltage) functional block for accelerations of 1 to 50 g. This paper reviews the rationale for surface micromachining the sensing element, the BiMOS2C integrated process, the sense and control circuit architecture, and performance of the chip.

Single-chip surface-micromachined integrated gyroscope with 50/spl deg//hour root allan variance

A MEMS surface-micromachined gyroscope integrated on a single 3/spl times/3 mm/sup 2/ chip with a 3 /spl mu/m BiCMOS process has 4 /spl mu/m-thick polysilicon structure, 5V 6 mA power supply, 0.05/spl deg///spl radic/s spot noise, 12.5 mV//spl deg//s, >30,000 g shock survival, and -55 to 85/spl deg/C operating range.