Bandwidth vs ZRO Stability Trade-Off in Lissajous Frequency Modulated MEMS Gyroscopes

The research highlights a significant challenge in microelectromechanical system (MEMS) gyroscopes operated under Lissajous frequency modulation (FM). While providing excellent inherent scale-factor stability performance and scale-factor independence of the mode mismatch, this operating principle suffers from a strict requirement in the implementation of the motion amplitude control on the two axes. It is shown how, unless a few-Hz (only) bandwidth is targeted, different amplitude-gain control (AGC) designs are all challenged and give rise to spurious harmonics which, after additional demodulation, may turn into a spurious offset, which undermines the system stability performance.