Vibration-insensitive 61-MHz micromechanical disk reference oscillator

Abstract

A low phase noise oscillator referenced to a 61-MHz vibrating wine-glass disk resonator with anchor-isolating supports designed to suppress microphonics has posted (without any compensation) a measured acceleration sensitivity at least as good as Γ ~0.2ppb/g for vibration frequencies up to 2kHz and in all directions, yielding a vector magnitude Γ less than 0.5ppb/g. Remarkably, this result is at least 30 times better than previous work using a similar wine-glass disk resonator and is the best mark among MEMS-based oscillators to date, including those aided by feedback compensation circuits. It is also more than an order of magnitude better than an off-the-shelf crystal oscillator and is now comparable with low sensitivity oven-controlled crystal oscillators (OCXO's). Such low sensitivity to environmental vibration by a tiny uncompensated MEMS-based oscillator is expected to enable harsh environment and military applications that require stable and compact reference oscillators.