Design and performance analysis of PLL based self oscillation loop in vibrating gyroscope

摘要

A self oscillation loop in vibrating gyroscope based on the phase locked loop (PLL) was proposed and a phase error in the PLL was analyzed. The self oscillation loop is a nonlinear feedback loop, which keeps a self-generated and sustained oscillation. In vibrating type gyroscope, a structure needs a driving oscillation at resonant frequency, which is provided by the self oscillation loop. In order to sustain the loop to be stable oscillation and to operate at the precise resonant frequency of the gyroscope, phase locking condition is essentially needed. Phase locked loop is a suitable component for such a purpose. In oscillation loop, PLL provides exact phase shift to oscillate at the resonant frequency point over wide frequency range. However, the performance of the PLL is affected by certain condition of the circuit, e.g. phase error due to the variation of the component values and noise-sensitive features. This directly leads the performance degradation of the gyroscope. Therefore, phase error analysis of PLL was performed and the robust phase shifting circuit was newly suggested. The experiments were accomplished to verify the suggested method.