MEMS oscillators are much less sensitive to vibration. Electronic systems are often exposed to environmental stresses such as vibration, especially systems that are deployed outdoors. Wind, heavy vehicles and trains are a few examples of the many sources of external vibration. Internal to many systems are cooling fans which are another source of vibration stress. These vibration stresses can induce frequency shift and noise on the crystal resonator. In extreme cases, vibration can cause system failure and service interruption, especially in systems that need a very stable frequency reference such as wireless base stations and small cells. A key reason MEMS oscillators are resistant to shock and vibration is because MEMS resonators have approximately 1,000 to 3,000 times lower mass than quartz resonators. This means a given acceleration imposed on a MEMS structure, such as from shock or vibration, will result in much lower force than its quartz equivalent and therefore induce a much lower frequency shift. This graph here shows the >10 times lower (better) vibration sensitivity of SiTime MEMS oscillators vs. quartz oscillators. (Note this graph here is based on measurements of quartz oscillators rather than passive crystal resonators, but comparable results are expected on quartz crystal resonators.)