Oscillators have historically been made from quartz crystal resonators connected to an analog sustaining circuit that drives the resonator to vibrate at a specific frequency. Now, there is an alternative – Silicon MEMS oscillators – and these devices outperform quartz oscillators in noisy environments. The drive toward higher speed telecom and mobile applications places greater demands on the clock source. Additionally, more complex electronics and higher clock frequencies necessitate that the clock device continue to perform well in noisy environments.
This paper shows results of comparative experiments that were conducted on quartz and Silicon MEMS oscillators. The data demonstrate that MEMS oscillators outperform quartz in realistic environmental conditions. Oscillator vendors provide data sheets for each product stating performance parameters such as frequency stability, jitter, and phase noise. While data sheets are a good indicator for selection of timing devices, the user must also evaluate how these devices perform in real-life environmental conditions. Testing under conditions that mimic those seen in the real operating environment provides valuable information about true component performance. The performance of oscillators subjected to environmental stressors, such as electromagnetic interference (EMI), vibration, and noise from power supplies or other system components, will degrade as compared to oscillators in ideal conditions. Ultimately, environmental stressors may reduce the reliability and lifetime of a device. It is important to consider the performance of oscillators under realistic, noisy, harsh conditions when selecting a timing device.