Microgyroscope control system using a high-order band-pass continuous-time sigma-delta modulator

The paper presents a novel 6th order continuous-time, force-feedback band-pass sigma-delta modulator control system for the detection mode of micromachined vibratory gyroscopes. Compared with the architecture using a low-pass sigma-delta modulator, this band-pass solution uses a much lower sampling frequency for the sigma-delta modulator and thus reduces the requirement for frequency response of the detection interface and control electronics. In this work, the sigma-delta modulator operates at only four times of mechanical resonant frequency, which allowed its implementation in a continuous-time circuit using discrete electronic components on a PCB; this has the advantage of simple prototyping and can improve the signal anti-aliasing characteristics.