Milli-Hertz Frequency Tuning Architecture Towards High Repeatable Micromachined Axi-Symmetry Gyroscopes

Axi-symmetry micro gyroscopes are increasingly popular for its ultra high measurement sensitivity. However, a side effect is the bias repeatability problem. In this paper, we propose and demonstrate an ultra-precise frequency tuning solution to achieve the state-of-the-art repeatability performance. The gyroscope dynamics are firstly analyzed and the major error source is confirmed as the frequency split. Then, an advanced frequency tracker and a precision tuning architecture are developed to improve the bias repeatability. The experimental results prove that the frequency tracker can identify the frequency splits at mHz level. Consequently, a state-of-the-art turn-on to turn-on bias repeatability of 3.6<inline-formula><tex-math notation="LaTeX">$^\circ$</tex-math></inline-formula>/hr is conducted that shows orders of magnitude better than conventional solutions.