Design of the digital interface circuit system for MEMS gyroscope

In this paper, a digital closed-loop measurement and control system of MEMS vibrating silicon gyro is proposed, which includes the sensitive structure model of gyro and the design of interface circuit. Because of the high sensitivity and precision of the MEMS gyroscope under the condition of modal matching, the measurement and control circuit is established under the condition of modal matching. The system uses automatic gain control (AGC) to control the amplitude of self-excited oscillation of the driving loop, which has the characteristics of simple and quick start. First, the working principle of gyro sensitive structure is introduced and an interface circuit with digital drive and detection mode is designed. Second, a high precision one-bit sigma-Delta (Sigma Delta) analogto-digital converter (ADC) is designed, and the signal-to-noise ratio (SNR) of the modulator is 102.5 dB at 10 kHz bandwidth. Third, a nonlinear multiplier is used in the driving loop to realize fast self-excited start-up of gyro, and a proportional integral (PI) controller is used in the self-excited loop to realize stable oscillation. Finally, Simulink is used to simulate and verify the sensitive structure model and the measurement and control system. The nonlinearity of the gyroscope is tested by experiment, and the well measurement and control precision of the gyro interface circuit is verified.