Electrical Noise in MEMS Capacitive Elements Resulting From Environmental Mechanical Vibrations in Harsh Environments

Many microelectromechanical systems (MEMS) devices possess charged capacitor structures where the suspension system allows relative electrode motion due to internal or external stimuli. When such a device is subjected to external mechanical vibrations present in a harsh operating environment, unwanted movement between the capacitor plates can generate a noise current which is injected into the connected circuitry. This paper analyzes this phenomenon and presents a model for the dynamics of a MEMS device with capacitive plates experiencing relative motion due to external stimuli. A Fourier series expansion of the current is developed to characterize the frequency content of the signal in closed form for a given vibration frequency, and simulation and experimental results are presented.