【作者】 陈宏；

【导师】 刘晓为； 陈伟平；

【作者基本信息】 哈尔滨工业大学 ， 微电子学与固体电子学， 2008， 博士

【摘要】 本文在建立全对称双级解耦微机械振动式陀螺理论模型的基础上,系统研究了器件的动力学特性。提出一种新颖的全对称双级解耦微机械振动式陀螺仪结构,利用体硅微机械加工技术实现了敏感结构芯片的制备,并进行了相应实验研究和特性测试工作。首先,工作带宽是微机械陀螺应用的一个重要指标,现有理论认为带宽和灵敏度是一对矛盾,将带宽简单定义为驱动频率与检测模态谐振频率之差。本文基于全对称双级解耦微机械振动式陀螺的理论模型,系统研究了器件的动力学特性,得出了工作带宽与频率匹配度以及检测模态品质因子有关的结论。当角速度的频率等于驱动模态与检测模态谐振频率之差时,灵敏度最大;保持驱动模态品质因子一定,改变检测模态品质因子Qy时,Qy存在一个临界值使检测方向峰值位移也满足3dB带宽的要求,大大扩展了陀螺的工作带宽。其次,提出了一种全对称双级解耦微机械振动式陀螺结构并利用体硅微机械加工技术制备了敏感结构芯片,该陀螺能实现模态频率匹配的同时降低模态之间的耦合。采用全对称结构,驱动模态和检测模态谐振频率容易匹配;双级解耦结构有效降低了驱动模态和检测模态之间的耦合;驱动梳齿和检测梳齿均采用滑膜阻尼结构,在常压下也能获得较高品质因子。考虑耦合弹性系数,建立器件的无阻尼自由振动模型以获得结构模态频率和振型。求解结果表明模态之间的耦合仅为1.56%,驱动和检测模态谐振频率均为2966.9Hz。应用ANSYS对微机械陀螺的模态频率进行了有限元求解,理论求解与有限元求解结果吻合较好。最后,基于对微机械陀螺动态特性的分析,设计了微陀螺开环检测接口电路。电路主要由C-V转换电路、高/低通滤波器、移相器以及相敏解调电路构成。采用所设计的开环检测微机械陀螺接口电路,对微机械陀螺模态特性、温度特性以及灵敏度等项目进行了测试。构建了显微镜测试平台对微机械陀螺非线性振动进行了测试。测试结果表明,驱动模态产生非线性振动时,谐振频率随振幅增大而增大。模态测试结果表明器件的频率匹配良好,谐振频率分布在2300Hz~2500Hz,与按照实际器件弹性梁宽度计算的谐振频率2774.7Hz较好吻合。温度特性测试表明随温度升高谐振频率和品质因子有所降低,但在不同的温度条件下模态频率仍匹配良好。在常压下测试微陀螺灵敏度为5.61mV/°/s,证实了该陀螺能在常压下工作。研究结果对全对称双级解耦微机械振动式陀螺的设计具有指导意义,为解决模态频率匹配、模态解耦以及避免真空封装等问题提供了一种解决方案。更多还原

【Abstract】 Based on the theoretical model of the fully-symmetrical and doubly-decoupled micromachined gyroscope, the dynamic characteristics of the device was researched systematically. A novel fully-symmetrical and doubly-decoupled micromachined gyroscope was presented and fabricated by bulk silicon micromachining technology. Further, corresponding experiments were performed to validate the research.Firstly, the working bandwidth is an important parameter for the application of MEMS gyroscopes. It was simply defined as the difference between the esonant frequencies of the drive mode and that of the sense mode, or the bandwidth and sensitivity of MEMS gyroscopes were regarded as a conflict qualitatively. Based on the systematical research of the dynamic characteristics of the presented gyroscope model, several conclusions were obtained. When the frequency of the input angular rate is equal to the difference of resonant frequencies between the drive mode and sense mode, the sensitivity reaches maximum. In the condition that the quality factor of the drive mode keeps constant, there is a critical value with the decrease of the quality factor of the sense mode, at which the peak sensitivity satisfies the 3dB bandwidth theory. Thus, the bandwidth is widened significantly.Secondly, a novel fully-symmetrical and doubly-decoupled micromachined gyroscope, fabricated by bulk micromaching technology, was presented. The fully-symmetrical structure enables the precisely matched frequency for the drive mode and sense mode. The doubly-decoupled structure reduces the cross coupling between the drive mode and sense mode. The free vibrating model without damping of the device was established and solved considering the couple elastic coefficient. The solution indicates that the model couple of the presented gyroscope is 1.56%, and the resonant frequencies of the drive and sense modes are 2966.9Hz. Also, the theoretical model was validated by the finite element model with the software package of ANSYS.At last, based upon the analysis of dynamic characteristic of micro gyroscope, an open-loop detecting circuit of micro-gyroscope was designed. This circuit was composed of C-V converting circuit, high/low pass filter, phase shifter and phase-sensitive demodulation circuit. The mode characteristic, temperature characteristic and sensitivity of micro gyroscope were tested with this testing board. The nonlinear vibration was tested by the established microscope experimental platform. The test results indicate that the resonant frequency increases with the vibration amplitude. The mode parameters tests prove that the two modes’resonant frequencies are well matched. The resonant frequencies distribute from 2300Hz to 2500Hz, which are in good accordance with the theoretical solution of the fabricated chip. The temperature characteristics tests indicate that resonant frequency and the quality factor decrease with the increasing of temperature, while the frequencies of the two modes match well. The measured sensitivity at atmospheric pressure is 5.61mV/°/s.The research presents a solution scheme for the frequency match, doubly-decouple, and capable of working at atmospheric pressure of MEMS gyroscopes. The work has some significance to the design of the fully-symmetrical and doubly-decoupled micromachined gyroscope.更多还原