Effects of combs on coupling error in the vibratory MEMS gyroscope with various air dampings

This paper presents the fourth order vibratory micromachined gyroscope prototype with coupling forces between two modes and the coupling error expression which reveals all the factors affecting the amplitude of the error. A detailed discussion has been performed to determine that the diversity of structures of drive combs and sense combs is the main source of the Quality factor in drive mode varying from that in sense mode, and different frequencies in which coupling error centralizes with various air dampings. It is demonstrated that coupling error centralizes in the drive mode resonance frequency in 1 atmosphere while the error in sense mode resonance ascends in the presence of higher vaccum based on the experimental and fitting curves, and sense mode has almost the same error magnitude as drive mode in 782 mtorr vaccum with the measured data. The analysis of combs´ effect on coupling error is significant for the optimization of comb structure, and provides a theoretical availability for the implementation of vaccum package and the greatly improved stability of MEMS gyroscopes.