Two-input axis angular rate sensor

A vibrating angular rate sensor is developed by the polysilicon surface mic romachining process. The 7.0 mu m-thick polysilicon layer is deposited by l ow-pressure chemical vapor deposition (LPCVD) and is suspended by sacrifici al oxide wet etching after patterning by reactive ion etching. The angular rate sensor uses angular resonance for the driving and sensing modes. The t wo-degenerate sensing modes enable the sensor to detect the angular rare in puts from each orthogonal substrate rotation. In view of cost and sizer one sensor chip is preferable to two sensor chips orthogonally-configured for the detection of two-input axis angular rate. The Coriolis motion arising f rom the angular rate causes the capacitance change and is converted to volt age change with signal conditioning hybrid application-specific integrated circuit (ASIC). The performance of the angular rate sensor is degraded by a ir damping, so the sensor element is housed in a high vacuum chamber for a high quality (Q) factor. The angular rate sensor has an active structure el ement less than 1 mm(2) in size and shows a noise equivalent signal of 0.1 deg/s.