一种高分辨率电容微加速度计的设计研究

分析了影响加速度计分辨率的因素,在此基础上,通过采用深度反应离子刻蚀工艺获得大的敏感质量和小的电极间隙、采用电容变化量比枝齿梳状敏感结构大一倍的直齿梳状敏感结构和利用静电负刚度来降低结构的刚度等措施提高器件分辨率。最后给出了一种新的设计方案,叙述了其工作原理并分析了影响其闭环灵敏度的因素。     

一种新型挠性轴内置式扭摆微加速度计的设计

针对扭摆式加速度计的结构特点,为了有效利用硅片面积和提高质量块质量,设计了一种新型挠性轴内置于质量块的扭摆式加速度计,该结构具有检测电极和力反馈电极.根据结构设计参数,推导出中心敏感电容、等效质量、机械灵敏度的参数表达式.利用扭摆加速度计的数学模型,建立了加速度计表头系统级模型,并结合接口电路进行闭环整体仿真,调整校正环节参数,得到闭环系统性能指标.最后进行初步开环测试,测得加速度计的灵敏度为33 mV/g,非线性度2.29%.     

基于光纤检测技术的扭转敏感微机电系统加速度传感器

为实现微型化、抗电磁干扰、可长时间工作和可远距离传输的加速度传感器,提出了一种基于微机电系统(MEMS)非对称扭镜结构的光纤加速度计设计方案,并利用对角度变化非常敏感的双光纤准直器对扭镜的扭转角度变化进行检测。MEMS光纤加速度计由MEMS非对称扭镜结构、驱动电极和双光纤准直器等组成。分析了器件的加速度敏感原理和光纤检测原理,介绍了器件综合设计考虑,并给出了器件的结构参数。利用MEMS加工技术成功制作了MEMS光纤加速度计样品。对加速度计进行了实验测试,加速度计的输出实验值与理论值吻合。测试结果表明,该加速度计量程为±2g,带宽为600 Hz,分辨率优于10-4 g,且具有良好的线性度和重复性。该MEMS光纤加速度计将MEMS敏感结构与光纤检测相结合,兼备了两者的优点,结构紧凑、制作工艺简单。     

梳齿差分电容式体硅微加速度计(英文)

提出了一种体硅微加速度计的设计和制造方法,同时设计了它的闭环反馈伺服电路,分析了加速度计的质量块、悬臂梁和梳尺间隙对量程、非线性、灵敏度、抗冲击能力和带宽等特性的影响。已经加工出的微加速度计,其全量程为±60g,非线性度0.2%,带宽1kHz,灵敏度200mV/g,抗冲击能力10kg。对由加速度计结构设计、温度和伺服电路造成的零位漂移现象进行了分析,提出了一种制造微加速度计的新颖MEMS工艺———正面释放体硅工艺。     

基于谐振原理的硅微机械加速度计

基于力学振动原理,导出敏感梁类谐振振动的微分方程,给出了振梁型加速度计的设计原理.指出了加速度计谐振梁频率的相对变化量与梁的厚度无关;为避免输出非线性频率信号,频率的相对变化率和激励振动的振幅都不宜太大.     

高量程加速度计横向各向异性响应的自由落杆冲击评估法（英文）

采用自由落杆冲击法对悬臂梁型高量程加速度计(50 000g)的横向响应进行研究。钢杆和铝合金杆作为冲击体与地面上放置的金属钢砧碰撞产生应力波作为激励源,用于表征加速度计的性能,其中加速度计固定在金属杆的顶端。该方法不仅可以测量加速度计敏感轴的灵敏度,同时也可以测试其横向响应。实验表明,加速度计的各向异性响应与加速度计的固有结构和冲击体的直径紧密相关,理论计算与实验结果相一致。     

一种新型挠性轴内置式扭摆微加速度计的设计

针对扭摆式加速度计的结构特点,为了有效利用硅片面积和提高质量块质量,设计了一种新型挠性轴内置于质量块的扭摆式加速度计,该结构具有检测电极和力反馈电极。根据结构设计参数,推导出中心敏感电容、等效质量、机械灵敏度的参数表达式。利用扭摆加速度计的数学模型,建立了加速度计表头系统级模型,并结合接口电路进行闭环整体仿真,调整校正环节参数,得到闭环系统性能指标。最后进行初步开环测试,测得加速度计的灵敏度为33mV/g,非线性度2.29%。     

三轴压阻加速度计的激光干涉法冲击校准

提出一种利用激光多普勒干涉法对高g值加速度计进行绝对法冲击校准的方法.本方法采用Hopkinson杆作为冲击加速度信号发生器,应用激光多普勒干涉仪可以精确地获得激励加速度脉冲的波形.对一种三轴压阻式加速度计的灵敏度校准实验证实了此方法的准确性,并对其横向效应进行了研究和讨论.     

一种新型挠性轴内置式扭摆微加速度计的设计

针对扭摆式加速度计的结构特点，为了有效利用硅片面积和提高质量块质量，设计了一种新型挠性轴内置于质量块的扭摆式加速度计，该结构具有检测电极和力反馈电极。根据结构设计参数，推导出中心敏感电容、等效质量、机械灵敏度的参数表达式。利用扭摆加速度计的数学模型，建立了加速度计表头系统级模型，并结合接口电路进行闭环整体仿真，调整校正环节参数，得到闭环系统性能指标。最后进行初步开环测试，测得加速度计的灵敏度为33mV/g，非线性度2.29%。     

左右分布式高灵敏硅微谐振加速度计结构设计

提出了一种基于微杠杆原理的左右分布式低交叉耦合、高灵敏度的硅微谐振加速度计结构.该结构采用了一级微杠杆放大机构,左右双音叉谐振器和单质量块布局,实现了力放大和差动频率输出,具有结构简单、易于加工的特点,且两音叉谐振器间相互干扰小.首先,优化了设计参数,并进行了模态分析与谐响应分析.结果表明,左右谐振工作谐振频率分别为149.49 kHz和150.8 kHz,在该工作频率下X方向的最大位移远大于y和Z方向(两个数量级以上),表明工作模态具有优良的抗干扰能力.其次,在1 000g加速度载荷作用下进行了极限过载仿真.仿真结果表明,其最大应力为612.69 MPa,表明具有一定的抗冲击能力.最后,在±50g的设计量程内对结构的灵敏度进行了仿真分析.仿真结果表明,其灵敏度为160.51 Hz/g,验证了该设计的正确性.     

一种实现自调谐频率综合器的算法和结构

在集成的频率综合器中 ,工艺、温度和电源电压的变化使得频率综合器产生的中心频率和频率调谐范围与期望值发生偏移。文中指出了一种自调谐频率综合器的算法和结构 ,利用特殊结构的可编程压控振荡器和自调谐算法实现宽调谐范围的频率综合器 ,进而充分涵盖期望的输出频段。用 0 2 5 μmCMOS工艺设计了一个中心频率 2 2GHz,调谐范围为 338MHz的频率综合器 ,用于IEEE80 2 11b/g无线局域网系统的超外差收发机中 ,可以充分满足标准要求的 80MHz的调谐范围 ;给出了锁定某一目标频率时自调谐算法的具体工作过程 ,结果表明该算法和结构是正确的。     

Low-loss and compact V-band MEMS-based analog tunable bandpass filters

This paper presents compact V-band MEMS-based analog tunable bandpass filters with improved tuning ranges and low losses. For compact size and wide tuning range, the two-pole filters are designed using the lumped-elements topology with metal-air-metal (MAM) bridge-type capacitors as tuning elements. Capacitive inter-resonator coupling has been employed to minimize the radiation loss, which is the main loss contributor at high frequencies. Two filters have been demonstrated at 50 and 65 GHz. The 65-GHz analog tunable filter showed a frequency tuning bandwidth of 10% (6.5 GHz) with low and flat insertion losses of 3.3 /spl plusmn/ 0.2 dB over the entire tuning range.     

An RC time constant auto-tuning structure for high linearity continuous-time /spl Sigma//spl Delta/ modulators and active filters

An automatic RC time constant tuning scheme is proposed for high linearity continuous-time g/sub m/-C and active RC circuits in a low power consumption environment. Instead of changing the g/sub m/ (in g/sub m/-C filters), the RC time constant is tuned by discretely varying the integration capacitors to preserve a high linearity. The auto-tuning circuit, consisting of an analog integrator, a voltage comparator, and a digital tuning engine, generates a control word and sets on-chip capacitors to obtain an RC time-constant accuracy of /spl plusmn/2-10%. The proposed scheme is verified by the experimental results of a test chip in a 0.5 /spl mu/m CMOS technology. It achieves a peak S/(N+D) of 83 dB while a tuning range of over /spl plusmn/40% is accomplished.     

Magnetic tuning of coaxial IMPATT oscillators

Frequency tuning of an IMPATT coaxial microwave oscillator, using variation of susceptibility of a 5 Oe linewidth y.i.g. sphere, is described. A deviation sensitivity of 2MHz/Oe is determined experimentally. Qualitative explanation is offered for the discrepancy between this value and the theoretically predicted sensitivity.     

Large-Scale Network Parameter Configuration Using an On-Line Simulation Framework

As the Internet infrastructure grows to support a variety of services, its legacy protocols are being overloaded with new functions such as traffic engineering. Today, operators engineer such capabilities through clever, but manual parameter tuning. In this paper, we propose a back-end support tool for large-scale parameter configuration that is based on efficient parameter state space search techniques and on-line simulation. The framework is useful when the network protocol performance is sensitive to its parameter settings, and its performance can be reasonably modeled in simulation. In particular, our system imports the network topology, relevant protocol models and latest monitored traffic patterns into a simulation that runs on-line in a network operations center (NOC). Each simulation evaluates the network performance for a particular setting of protocol parameters. We propose an efficient large-dimensional parameter state space search technique called “recursive random search (RRS).” Each sample point chosen by RRS results in a single simulation. An important feature of this framework is its flexibility: it allows arbitrary choices in terms of the simulation engines used (e.g., ns-2, SSFnet), network protocols to be simulated (e.g., OSPF, BGP), and in the specification of the optimization objectives. We demonstrate the flexibility and relevance of this framework in three scenarios: joint tuning of the RED buffer management parameters at multiple bottlenecks, traffic engineering using OSPF link weight tuning, and outbound load-balancing of traffic at peering/transit points using BGP LOCAL_PREF parameter.      

单脊条形可调谐电吸收调制DFB激光器

报道了一种波长可热调谐的电吸收调制分布反馈激光器(Electroabsorptionmodulateddistributedfeedbacklaser,EML)。在激光器条形的侧面淀积一薄膜加热器,EML实现了 2 2nm的连续调谐。在调谐范围内,激光器输出功率的变化小于 3dB。采用端面有效反射率方法和耦合波理论的计算表明:采用相调制方法,可实现调谐范围达3 2nm的EML。如果热调谐与相调谐方法结合,可在较宽范围内实现波长快速调谐的EML     

Single frequency electrooptical tuning of an extended cavity diodelaser at 1500 nm wavelength

A wavelength-tunable, single-frequency GaInAsP-InP laser diode using an intracavity electrooptic LiNbO₃ crystal as the wavelength selective component is discussed. Wavelength tuning is achieved by applying a driving voltage on the crystal electrodes. First results indicate a tuning rate of 1 GHz/V over a tuning range of about 4 nm. This performance was obtained using a nonoptimized X-cut, Z-propagating LiNbO₃ crystal. A potential tuning rate of 6.5 GHz/V is possible with reasonable improvements     

High- RF-MEMS 4–6-GHz Tunable Evanescent-Mode Cavity Filter

This paper presents a miniature high- $Q$ tunable evanescent-mode cavity filter using planar capacitive RF microelectromechanical system (MEMS) switch networks and with a frequency coverage of 4.07–5.58 GHz. The two-pole filter, with an internal volume of 1.5 cm$^3$ , results in an insertion loss of 4.91–3.18- and a 1-dB bandwidth of 17.8–41.1 MHz, respectively, and an ultimate rejection of $>$ 80 dB. RF-MEMS switches with digital/analog tuning capabilities were used in the tunable networks so as to align the two poles together and result in a near-ideal frequency response. The measured $Q_{u}$ of the filter is 300–500 over the tuning range, which is the best reported $Q$ using RF-MEMS technology. The filter can withstand an acceleration of 55–110 g without affecting its frequency response. The topology can be extended to a multiple-pole design with the use of several RF-MEMS tuning networks inside the evanescent-mode cavity. To our knowledge, these results represent the state-of-the-art in RF-MEMS tunable filters.      

X-band RF MEMS tuned combline filter

A three-pole combline filter tuning from 8.2 to 11.3 GHz using RF MEMS switched capacitors is reported. This structure, measuring 2.85/spl times/2.15 mm/sup 2/, allows 31% tuning with 11% 3 dB bandwidth for the four tuning states and insertion losses ranging from 4.4 to 6 dB.     

A micropower CMOS continuous-time filter with on-chip automatic tuning

This paper presents a CMOS implementation of a low-voltage micropower G/sub m/-C biquad with on-chip automatic tuning. The filter is suitable for any kind of application involving low-frequency ranges, and very low-power consumption, such as biomedical devices. The operational transconductance amplifier (OTA) is implemented with the transistors working in the weak inversion saturation region, thus allowing the use of very small currents that minimize the power consumption. The aspect ratios are small enough not to degrade the frequency response. The tuning algorithm is based on amplitude tracking. The filter output amplitude is quantized using a low-power amplifier and an asymmetric comparator. A digital controller varies the tuning parameters until the maximum quantized amplitude is found. The system works down to a voltage supply of 1.75 V. The center frequency is tunable over one and a half decades, from 300 Hz to 10 kHz for bias currents changing from 6 to 200 nA and a 20-pF integrating capacitance, giving an overall filter accuracy of up to 99.55%. The power consumption of the second-order filter including the common-mode correction circuitry is in the order of 200 nW for the 10-nA bias current. It exhibits a dynamic range of 54 dB and occupies an area of 0.06 mm/sup 2/ excluding the area of the integrating capacitances.