The Oven-Controlled MEMS Oscillators in Timing and Sensing Applications: A Review
Tianren Feng, Quan Yuan, Duli Yu, Bo Wu, Hui Wang
Abstract
Compared to conventional sensors, resonant-based sensors output frequency signals instead of voltage signals and therefore have greater advantages in terms of accuracy, noise resistance, and miniaturization. However, the resonant frequency is sensitive to temperature variation. The oven-controlled MEMS oscillators (OCMOs) have proven to be the most promising candidate for highly accurate oscillators. Therefore, when the OCMO is used for timing and sensing applications, better device temperature stability and performance are expected. However, OCMOs are still in the development stage from laboratory to commercial products, and there are few related reviews about OCMOs. This article reviews typical results of OCMOs in the past decade with the aim of supporting the development of frequency reference and resonant-based sensors. We emphasized the importance of temperature control for OCMOs. Then, the basic concepts and models of the OCMO are introduced, and the development trend of the OCMO is discussed from three aspects: device structure, sensing mechanism, and heating control systems. Finally, the fabrication process, conclusion, and outlook are given.