MEMS振荡器电路非线性相位噪声机理的实验研究

MEMS oscillator may be expected to replace the active quartz crystal to get extensive market applcation due to low cost and DFM characteristics. However, the phase noise performance can not arrive at the requirement of signal communication, high-precision sensors and high-end applications due to poor understanding of noise physics based mechanism. Our preliminary work initially completed the theoretical analysis of the MEMS oscillator phase noise mechanism, and numerical simulation based circuit experiment. Our theoretical model breaks down the assumption of the chaotic mechanism by Clark, Nguyen, et al., and is consistent with the numerical simulation results ,but a little different from the circuit experimental results .To solve this problem , this project performs intensive theoretical and experimental work, to experimentally verify mechanism of the phase noise, and to improve the theoretical model, in order to find the method to suppress phase noise. This project results together with the previous work consist of a complete study on MEMS oscillator phase noise mechanism , which provides a theoretical basis, experimental evidence and design solutions for us to greatly enhance the performance of the MEMS time basis and the resonant sensor, which breaks down the bottleneck of high-precision applications, realizing the MEMS resonator mass industrialization

MEMS振荡器具有批量生产、低成本的优点，有望取代有源石英晶振，应用前景巨大。然而目前其相位噪声性能还达不到通信、高精度传感器等高端应用的指标，原因是由于对其机理认识不够深入。我们的前期工作初步完成了MEMS振荡器相位噪声机理的理论体系构建，并进行了数值仿真与初步的电路实验研究。我们的理论模型推翻了Clark Nguyen等人提出的混沌机理假设，且与数值仿真结果相符，但与电路实验的结果存在差异。针对这一问题，本课题将展开深入的理论与实验研究，探明并实验验证相位噪声的机理，完善理论模型，从而寻找抑制相位噪声的方案。本课题的研究工作，与前期工作一起构成完整的MEMS振荡器相位噪声机理的研究，为大幅度提升MEMS时间基准及谐振式传感器的性能，突破其高精度应用的瓶颈，实现MEMS谐振器大规模产业化，提供理论基础、实验依据及解决方案。

振荡器是电子系统的关键元件之一，它提供周期性的振荡信号，作为系统时钟。它的相位噪声性能决定了系统所能达到的极限性能，也是系统功耗的决定性因素。然而振荡器虽然结构简单，却是非常非线性的系统，却有着复杂的动力学行为。深入的理解振荡器系统有助于电路工程师与系统设计师优化振荡器电路的设计，加速设计周期，用最少的代价来逼近极限性能。本课题对振荡器的进行了系统的研究，深入研究了振荡器相位噪声的机理，完善了理论模型，修正了传统理论关于电流效率的推导，将传统模型中2/pi的极限修正为0.85。提出了新型数字控制振荡器的技术方案，能同时提升数字调节的分辨率与相位噪声性能。提出了一种利用基于差分结构schmitt触发器回滞曲线与绝对温度成正比的特性的振荡器结构，实现了低功耗高稳定性的片上振荡器。研究了MEMS体声波振荡器，建立了它的等效电气模型，研究了它的脉冲模式驱动与电容检测的技术方案，以改善其噪声性能与频率分辨率，并测试了它在湿度检测中的性能。