M.Sc Thesis

M.Sc StudentZaltzman Ido
SubjectSelf-Excited Mems Oscillators
DepartmentDepartment of Mechanical Engineering
Supervisor PROF. David Elata
Full Thesis textFull thesis text - English Version


Self-excited oscillators are systems which react in a periodic response when subjected to a constant input loading. In this work two kinds of such systems are considered. The first self-excited oscillator is an Ohmic switch. For a sufficiently high DC voltage, the electrodes of the Ohmic switch are electrostatically attracted and eventually make contact, and consequently discharge and reopen. Due to the constant loading, these two response steps are sequentially repeated, resulting in continuous oscillations. In this work the cyclic response of the Ohmic switch oscillator is moderated by a large resistor. This resistor dominates the charge time of the system and hence dominates its frequency.

The second self-excited oscillator is the Franklin oscillator which is named after Benjamin Franklin (1706-1790) - even though it was most likely first invented by Andrew Gordon in 1742. The Franklin oscillator is constructed from two electrodes which are subjected to different constant potentials, and a floating conductor which repeatedly transfers electrostatic charge between them.

Both types of self-excited oscillators are investigated analytically to derive the underlying characteristics of their respective dynamic response. In addition, simple macro-scale models were built in order to obtain an experimental qualitative validation, and their results are presented.