Comparison of DSB and SSB demodulation methods in general control system of MEMS gyroscopes
This paper reports a comparative study between double side-band (DSB) and single side-band (SSB) demodulation methods when applied to a general control system of MEMS gyroscopes. Theoretical analysis originally reveals the influence of phase delay variations of C/V sensing circuit in the drive loop on gyroscope output. A simulation is set up to evaluate the two demodulation algorithms, demonstrating reliable robustness against the aforementioned phase delay variations using DSB algorithm, which is due to the fully decoupling between the angular rate output and quadrature output. Further, comparative experiments of control systems respectively based on DSB and SSB are conducted, using an FPGA-based digital platform on a MEMS gyroscope. Experimental results indicate that the system using DSB demodulation method has better performance, with angle random walk (ARW) of 0.14 °/√hr and bias instability of 1.18 °/h, than the system using SSB demodulation method with the measured ARW of 0.22 °/√hr and bias instability of 3 °/h.