Design Of Self-Excited Sinusoidal Driving Circuit Of Quartz Tuning Fork Gyroscope

Quartz tuning fork gyroscope is a measurement of the angular velocity of inertial sensors, which contains sense structure of quartz and signal processing circuit, the circuit achieved by using integrated circuit technology, with a small size, light weight, low cost, mass production and precision. It is widely used in the aerospace, military guidance, and undersea exploration. This paper analyzes the electrical properties of quartz crystal to establish the equivalent electrical model of quartz tuning fork. Propose a sinusoidal self-excited driving circuit with automatic gain control. Then, draw the layout of this circuit. Also, do post simulation of designed layout.First, we utilize the dynamic equation of quartz tuning fork gyroscope to establish the equivalent electrical model of the quartz tuning fork. And do the AC small signal simulation of this equivalent model to get the amplitude and phase frequency characteristics of the sense current produced by the quartz tuning fork. We find that, when the frequency of driving signal is same to the quartz crystal resonant frequency, the amplitude of the sense current reaches the max value.Second, we compare the self-excited manner and external AC voltage drive manner, while we make a simulation to select driving signal between square wave and sine wave. Then, we determine to adopt sinusoidal self-excited driving structure with automatic gain control model, including I/V conversion circuit, peak detection circuit, variable gain amplifier and post amplifier circuit. Afterward, we use Matlab Simulink building an ideal model of self-excited sinusoidal drive system to verify the feasibility of the scheme.Finally, we design the transistor circuit and layout of the driving system according to the scheme, and do preceding simulation and post simulation each. The simulation results is that, drive signal peak value is 5.7886V, the driving frequency is 11811.0Hz, the vibration driving setting time of drive circuit is less than 1 second, amplitude stability and frequency stability is 0.3% and 0.8%, respectively. Based on these results we can conclude that the self-excited sinusoidal driving circuit we designed is able to meet the requirements of quartz crystal structure, and it can provide a sinusoidal drive signal with stable amplitude and frequency for the test circuit.