Design of Digital Demodulation Circuit for Closed Loop Control of Resonant MEMS Gyroscopes

The stability of the motion of the gyro drive axis is an important factor in determining the performance of the resonant MEMS (Micro-Electro-Mechanical System) gyroscope. In order to ensure the stability of the output signal of the drive axis, it is necessary to perform closed loop control on the driving axis and the detection axis of the gyro. In this paper, a digital demodulation circuit is proposed and designed to detect the orthogonal component and the in-phase component of the gyro drive axis and the detection axis. Additionally, the drive voltage of the drive axis and the balance voltage of the detection axis are generated by the digital controller to realize closed loop control. The RTL (register transfer level) simulation verified the effectiveness of the digital demodulation algorithm. The experiment verified the entire digital system including signal demodulation and closed loop control. Under zero angle input conditions, the results shown that for the drive axis output signal, the amplitude relative error is less than 0.001, and the frequency was consistent with the set value. Additionally, the amplitude error of the detection axis was suppressed to near 0.