高频MEMS振荡器性能研究

发布时间：2018-05-06 11:37

  本文选题：射频微机电 + 谐振器　； 参考：《电子科技大学》2015年硕士论文

【摘要】：随着电子系统对高性能、小型化器件需求的逐步增长,MEMS振荡器凭借其高Q值、易集成、抗冲击等优异性能成为研究热点。本文旨在探究高频MEMS振荡器的性能,而谐振器作为振荡器的核心部件,自然成为研究的重点。文中设计了一种新型的带有可动电极的10MHz MEMS方块谐振器。着重研究了降低谐振器动态阻抗的移动电极法。电极与谐振方块初始间隙为2.5μm,当加载60V偏置电压后,通过静电力作用使二者间距减小至0.5μm。此时,通过ANSYS谐波仿真得知谐振器动态阻抗减小至初始值的1/626。在不增加工艺难度的前提下,将器件的深宽比从10:1提升到50:1。基于体硅加工的工艺特性,给出了谐振器的微加工流程,利用L-EDIT完成了固定电极与可动电极两种谐振器的版图设计,实现了两种类型谐振器的加工,并采用真空探针台完成了谐振器裸片测试,定性地分析了其谐振器谐振频率产生0.552MHz偏移的原因。针对谐振器工作的真空环境要求,研究了其封装所需条件,对谐振器进行了金属封装。运用矢量网络分析仪完成了封装后谐振器的测试,评估了金属封装对谐振器性能的影响。采用机电类比法,根据谐振器机械特性与电气特性之间的映射关系,将谐振器的机械集总参数模型转化成了对应的电气集总等效电路模型。针对谐振器电路模型的输出特性,引入了差分法消除谐振器馈通电容的方法。依据测试数据,通过仿真拟合出谐振器RLC电路模型中各参数值。选用性能比较优异的固定电极MEMS方块谐振器进行了MEMS振荡器的设计。由ADS电路仿真得MEMS振荡器的主要性能如下:输出信号频率为9.448065MHz,输出信号功率14.205d Bm;各阶偶次谐波输出功率均低于-350dBm,几乎可以忽略不计;MEMS振荡器输出噪声性能:-100.370dBc/Hz@0.1Hz,-103.565dBc/Hz@1Hz,-120.197dBc/Hz@10Hz,-122.784dBc/Hz@100Hz,-122.777dBc/Hz@1kHz。
[Abstract]:With the increasing demand of electronic systems for high performance and miniaturization devices, MEMS oscillators with high Q value, easy integration, impact resistance and other excellent properties have become the focus of research. The purpose of this paper is to explore the performance of high frequency MEMS oscillators, and the resonator, as the core component of the oscillator, naturally becomes the focus of the research. A new type of 10MHz MEMS square resonator with movable electrode is designed in this paper. The method of moving electrode to reduce the dynamic impedance of resonator is studied emphatically. The initial gap between the electrode and the resonant square is 2.5 渭 m. When the bias voltage of 60V is loaded, the distance between the electrode and the resonator is reduced to 0.5 渭 m by electrostatic action. At this point, the ANSYS harmonic simulation shows that the dynamic impedance of the resonator is reduced to 1 / 626 of the initial value. Without increasing the process difficulty, the aspect ratio of the device was raised from 10:1 to 50: 1. Based on the process characteristics of bulk silicon machining, the micromachining process of resonator is given. The layout design of fixed electrode and movable electrode is completed by using L-EDIT, and two types of resonators are machined. The vacuum probe table is used to test the resonator's bare chip, and the reason of the 0.552MHz shift of the resonator's resonance frequency is analyzed qualitatively. According to the vacuum environment requirement of the resonator, the conditions of its packaging are studied, and the metal packaging of the resonator is carried out. The effect of metal encapsulation on the performance of the resonator was evaluated by using vector network analyzer. According to the mapping relationship between mechanical and electrical characteristics of resonator, the mechanical lumped parameter model of resonator is transformed into the corresponding equivalent circuit model of electrical lumped circuit by electromechanical analogy method. According to the output characteristics of the resonator circuit model, a differential method is introduced to eliminate the feed-through capacitance of the resonator. According to the test data, the parameters of the resonator RLC circuit model are simulated. The MEMS oscillator is designed by using a fixed electrode MEMS box resonator with excellent performance. The main performances of the ADS oscillator are as follows: the output signal frequency is 9.448065MHz, the output signal power is 14.205dBm, the output power of every order harmonic is lower than -350dBm, and the output noise performance of the MEMS oscillator is almost negligible: -100.370 dBc / Hz-103.565dBcHz-120.197dBc / Hz-122.784dBccP / Hz100Hz-122.777dBcHcP / HzP / HzP = 1kHz.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN752
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本文编号：1852163