Vibration Analysis and Control of the Quartz Rate Sensor

BEI Systron Donner’s family of quartz inertial sensors uses a one piece, micromachined inertial sensing element to measure angular velocity. These sensors produce an output signal proportional to the rate of rotation sensed. In this paper, the operation of the quartz rate sensor (QRS) is presented. A mathematical model of the quartz fork is extracted, and the vibration characteristics of the quartz fork are presented. In order to control the magnitude of the drive tines, an AGC/Oscillator (AGC: automatic gain control) loop is employed. The system response is analyzed using Matlab and Pspice. A switched capacitor (SC) circuit is used to realize the functions of full wave rectification (FWR), integration, and summation. The AGC level is controlled to within 0.3%/V dependency on the power supply. This fixes the scale factor of the QRS to the same level of power supply rejection.