Performance comparison of integrated z-axis frame microgyroscopes

This paper describes two different integrated surface-micromachined z-axis frame gyros fabricated side by side on a single chip for performance comparison. Frame microgyros; using an ´Inside Sense Outside Drive (ISOD)´ and an ´Inside Drive Outside Sense (IDOS)´ suspension designs were fabricated in the Analog Devices Modular-MEMS process using 6 μm thick polysilicon as the structural material co-fabricated with a 0.8 μm CMOS process. Initial characterization of these gyros suggest the ISOD frame gyro has a factor of three lower quadrature and Coriolis offset and a factor of five lower noise floor (limited by electronic noise) in comparison with the IDOS frame gyro. The surface-micromachined z-axis ISOD frame gyro exhibited a noise floor of 0.01°/s/√Hz and a scale factor of 1.5 mV/°/s at 70 milli-Torr pressure.