A MEMS-Stabilized AC Voltage Reference Source

Two electronic circuits are described in which the pull-in voltage of capacitive microelectromechanical system (MEMS) devices is applied as a reference for a stable alternating voltage source at frequencies between 5 kHz and 100 kHz. The first circuit is a simple harmonic oscillator. This low-cost circuit is capable of achieving a stability of better than 10 muV/V over one day. The second circuit shows a concept for a self-adjusting feedback technique. The circuit adjusts itself to operate the MEMS capacitor at its pull-in voltage