Actuation of a Frequency Modulated MEMS Gyroscope

This paper describes an analog actuation circuit for a novel frequency-modulated MEMS gyroscope. The circuit provides an amplitude-modulated (AM) signal as the input into a RLC resonant drive circuit, which drives the gyroscope. The actuation system is composed an automatic gain control (AGC) loop, a low pass filter, an amplitude modulation component and a resonant drive circuit. The AM signal is composed of a modulating signal that excite a natural frequency of gyroscope drive mode and a carrier signal with a frequency corresponding to the electrical resonant frequency of the RLC circuit. Both feedforward and feedback AGC configurations are used to stabilize the envelope of the signal. However, the breadboard implementations of the feedforward and feedback circuits in their current configurations have similar signal to noise ratio to that of the function generator. To improve the actuation circuit performance, we plan to include the resonant drive circuit within the AGC feedback loop and implement the actuation circuit on PCB.