Abstract: A closed loop sensor that utilizes a piezoelectric structure. In one embodiment, driven/non-control electrodes apply drive voltages to the piezoelectric structure and drive/control electrodes apply drive/control voltages to the piezoelectric structure to cause drive mode displacement of the piezoelectric structure and cancel motion induced pickup mode and quadrature displacements of the piezoelectric structure. In another embodiment, pickup/control electrodes detect a pickup signal from the piezoelectric structure corresponding to the motion induced pickup mode and quadrature displacements and apply a control signal to the piezoelectric structure so as to cancel these displacements. In still another embodiment of the invention, an optical sensing device optically senses the motion induced pickup mode and quadrature displacements and control electrodes apply a control signal to the piezoelectric structure so as to cancel them.

Abstract: Accelerometer and method in which parts such as the seismic mass and force sensors are all fabricated of a single material such as crystalline quartz and bonded together in a manner which reduces the possibility of creep between them. Damping plates and squeeze film gas damping dampen movement of the seismic mass, and the parts are oriented in a predetermined manner relative to the crystallographic axes of the wafers from which they are fabricated to control the character of breakaway tabs which hold the parts to the wafers during fabrication.