Digital circuit design to improve drive signal amplitude stability of quartz tuning fork gyroscope

The quartz tuning fork gyroscope usually adopts analog demodulation circuit, and the drive amplitude of analog circuit has the problem of low stability, which limits the performance of the gyroscope. In this paper, the digital circuit was used to improve the stability. First, the reason that drive signal amplitude stability could affect the gyroscope performance was analyzed. Then, the digital circuit and digital signal processing algorithm were designed to realize the digital closed loop driving. Finally, the drive amplitude stability of both the analog circuit and the digital circuit were tested. The test results show that, when in the condition of constant temperature, the mean-square deviation of the driving amplitude in analog circuit is 4.77×10 ^-4V, and it is 8.26×10 ^-5 V in digital circuit. When the temperature is changed from -40°C to 80 °C,the mean square deviation of the driving amplitude in analog circuit is 0.0680 V, and it is 0.0006 V in digital circuit. These verify that the drive amplitude stability is improved significantly using the digital circuit.