MEMS Torsional Pendulum Gyroscope With Fishbone-Like Sense Electrodes for Minimizing Quadrature Electrical Readout

This letter presents a microelectromechanical system (MEMS) torsional pendulum gyroscope with fishbone-like sense electrodes for minimizing electrical readout errors caused by mechanical quadrature coupling. Due to Poisson effect, the inherent mechanical quadrature coupling from drive motion induces torsional displacements in sense electrodes, causes sense capacitance changes, and hence results in electrical quadrature signals. Fortunately, these unwanted electrical quadrature signals can be eliminated by adjusting the angle between the proposed fishbone-like sense electrode and the sense direction, due to the reverse deformations of the capacitive gaps within the fishbone-like sense electrode. Measurement results illustrate that the quadrature electrical readout varies with the angle of the sense electrode, which agrees well with the theoretical calculation as well as the finite element method (FEM) analysis. With an optimal angle, the reported MEMS gyroscope exhibits a low initial quadrature coupling error of 39°/s, a bias instability of 1.13°/h, and an angular random walk of 0.38°/<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sqrt {\text {h}}$ </tex-math></inline-formula>. It highlights an effective approach for minimizing the electrical readout errors caused by mechanical quadrature coupling and hence enhancing device performance for MEMS gyroscopes.