An amplitude regulation for gyroscope drive loops based on phase-shifting

To achieve high quality measurements with micro gyroscopes it is essential to maintain a primary oscillation with a constant amplitude for a reliable detection of angular rotations with the Coriolis effect. This paper presents a self-oscillation drive loop for gyroscopes with a new amplitude regulation based on phase shifting. Instead of regulating the driving stage in order to control the oscillation amplitude of the primary mass to a constant value, this concept introduces a variable phase delay between the velocity of the primary mass and driving force in a self-oscillation drive loop. A Schmitt trigger with a tunable hysteresis is used to generate the necessary phase delay. Compared to conventional amplitude regulation this concept is beneficial, since the high voltages of the driving stage can be set to a constant value and do not have to be adjusted. As a result the analog circuit complexity is enormously reduced. Simulation results show the principle of maintaining the sensor deflection by a phase shifting element.