抗过载微陀螺结构的高灵敏设计与仿真

为解决高过载微陀螺难以实现高灵敏检测的问题,设计了一种高灵敏且高过载的微陀螺结构。设计的微陀螺结构驱动模态与检测模态的频率高度匹配,提高了微陀螺的结构灵敏度。该微陀螺采用面内检测方式,驱动与检测模态阻尼类型主要为滑膜阻尼,实现了在大气压环境下微陀螺的高品质因数Q值设计。微陀螺均采用双悬臂梁设计,增加了微陀螺结构的稳定性,进而提高了其抗过载能力。最后通过微陀螺的器件级仿真,得到了所设计陀螺结构在驱动方向过载能力约为100 000g(g=9.8m/s~2),检测方向过载能力约为70 000g的前提下,结构灵敏度为53nm/[(°)/s]。     

大气下工作的微机械陀螺的设计及其噪声特性

设计了一种基于体微机械加工技术的新型音叉式微机械陀螺．该陀螺在驱动模态和检测模态的空气阻尼均为滑膜阻尼，有效提高了微机械陀螺的Q值和灵敏度,同时降低了陀螺的热机械噪声．对陀螺噪声特性进行的分析表明，该陀螺具有相对很低的热噪声．制作了陀螺芯片，并测试了其机械性能和噪声特性．结果表明，该陀螺的噪声谱密度不超过60μV/Ｈｚ1/2，灵敏度为10mV/（°·s－１）．该微机械陀螺有望实现较高的角速度分辨率．     

双框架解耦微陀螺原理样机研制

为了把驱动工作模态和检测工作模态有效隔离,以减小模态间的互相干扰,设计了一种双框架解耦微机械陀螺。通过采用可工程化的鲁棒优化结构设计和工艺补偿的制造工艺,实现了工艺误差范围内的稳健设计。这种内外框架结构的微陀螺设计,包括自激闭环驱动电路和开环检测电路,对微陀螺进行测试,得到微陀螺驱动模态品质因素〉2000,检测模态品质因素〉800,量程为2400°/s,线性度〈0.3%,灵敏度为1°/s。     

大气下工作的微机械陀螺的设计及其噪声特性

设计了一种基于体微机械加工技术的新型音叉式微机械陀螺.该陀螺在驱动模态和检测模态的空气阻尼均为滑膜阻尼,有效提高了微机械陀螺的Q值和灵敏度,同时降低了陀螺的热机械噪声.对陀螺噪声特性进行的分析表明,该陀螺具有相对很低的热噪声.制作了陀螺芯片,并测试了其机械性能和噪声特性.结果表明,该陀螺的噪声谱密度不超过60μV/Hz,灵敏度为10mV/(°·s-1).该微机械陀螺有望实现较高的角速度分辨率.     

旋转式硅微机械陀螺的研究

分析了旋转式硅微机械陀螺的工作原理，建立了该陀螺的数学模型，设计了其敏感结构，计算了陀螺振动元件三个轴向的转动惯量、弹性支撑梁扭转刚度、振动元件角振动阻尼系数等动力学参数，计算分析了陀螺的电容敏感特性。对制作的陀螺进行性能测试的结果表明，该陀螺利用旋转载体自身的旋转角速度作为驱动，从而说明敏感载体的俯仰（或横滚）角速度原理正确，并且理论和试验都说明，当载体自旋角速度不同时，陀螺输出信号的比例系数也不同。     

MEMS陀螺中带孔结构空气阻尼建模分析

针对MEMS陀螺中带孔结构的空气阻尼问题,根据制作的微陀螺,利用MATLAB软件对模态匹配、Q值匹配与灵敏度之间的关系进行了仿真分析。仿真结果表明在驱动和检测模态匹配时灵敏度幅值最大,但工作带宽却随Qx与Qz乘积的增大而减小。建立了空气阻尼计算模型,并利用实验测试数据对空气阻尼计算模型进行了分析和检验。研究发现,微陀螺在驱动方向上,带孔平板结构的滑膜空气阻尼计算模型存在一定误差,经过系数修正后Q值的理论值与测试值具有较好的一致性,但仍需要进一步地修正和完善;在检测方向上,压膜空气阻尼模型比较准确,精度较高能控制在5%以内,可直接用于微陀螺的空气阻尼设计中。     

微机械梳状陀螺仪的瞬态分析

为了研究微陀螺敏感模态和驱动模态的固有频率与机械灵敏度以及相位漂移、稳定性的关系，利用敏感电压的负刚度效应调节两模态间的固有频率差，通过CovcntorWare软件进行瞬态分析，经优化仿真后得到了在一定的频率差下微陀螺的最佳性能。     

旋转载体用硅微机械陀螺的动力学分析与仿真

提出一种“旋转载体用硅微机械陀螺”，给出了该陀螺敏感头的结构尺寸，对陀螺角振动方程中出现的转动惯量、弹性支撑梁的扭转刚度系数和角振动阻尼系数分别进行了解析近似计算，得到了角振动幅度与被测角速率的关系曲线。用ANSYS仿真分析软件对陀螺结构进行模态分析和谐响应分析，比较计算机模拟和解析近似计算结果，它们相差不大，从而使两种处理方法相互得以验证。     

旋转式硅微机械陀螺的研究

分析了旋转式硅微机械陀螺的工作原理,建立了该陀螺的数学模型,设计了其敏感结构,计算了陀螺振动元件三个轴向的转动惯量、弹性支撑梁扭转刚度、振动元件角振动阻尼系数等动力学参数,计算分析了陀螺的电容敏感特性.对制作的陀螺进行性能测试的结果表明,该陀螺利用旋转载体自身的旋转角速度作为驱动,从而说明敏感载体的俯仰(或横滚)角速度原理正确,并且理论和试验都说明,当载体自旋角速度不同时,陀螺输出信号的比例系数也不同.     

旋转式硅微机械陀螺的研究

分析了旋转式硅微机械陀螺的工作原理,建立了该陀螺的数学模型,设计了其敏感结构,计算了陀螺振动元件三个轴向的转动惯量、弹性支撑梁扭转刚度、振动元件角振动阻尼系数等动力学参数,计算分析了陀螺的电容敏感特性。对制作的陀螺进行性能测试的结果表明,该陀螺利用旋转载体自身的旋转角速度作为驱动,从而说明敏感载体的俯仰(或横滚)角速度原理正确,并且理论和试验都说明,当载体自旋角速度不同时,陀螺输出信号的比例系数也不同。     

On the zero-crossing distortion in single-phase PFC converters

Input current distortion in the vicinity of input voltage zero crossings of boost single-phase power factor corrected (PFC) ac-dc converters is studied in this paper. Previously known causes for the zero-crossing distortion are reviewed and are shown to be inadequate in explaining the observed input current distortion, especially under high ac line frequencies. A simple linear model is then presented which reveals two previously unknown causes for zero-crossing distortion, namely, the leading phase of the input current and the lack of critical damping in the current loop. Theoretical and practical limitations in reducing the phase lead and increasing the damping factor are discussed. A simple phase compensation technique to reduce the zero-crossing distortion is also presented. Numerical simulation and experimental results are presented to validate the theory.     

Computer Detection of Distortion in Arterial Pressure Signals

An application of the mathematical concept of curvature to the detection of distortion in arterial pressure signals is described. Curvature is defined and examples of digitally filtered pressure tracings show the relationship between curvature and the degree of damping. Even though curvature is also a function of the cardiovascular system producing the signal, the average sum of curvature can generally distinguish control signals from signals distorted by moderate amounts of blood or air in the catheter systems. Selected pressure signals with their associated sums of curvature show the properties and limitations of curvature for discriminating between the changes in the cardio-vascular system and distortion of pressure signals.     

单模半导体激光器的非线性失真特性的电路模拟

本文提出了一种基于小信号等效电路的半导体激光器非线性电路模型，该模型使激光顺的调制响应和非线性特性以及其它相关电子电路的非线性特性可统一地通过通用电路分析软件来分析和计算。运用此模型对一单模激光器的二阶谐波与三阶交调失真特性进行了分析，结果与已报道的理论和实验结果一致。     

High speed nano-scale positioning using a piezoelectric tube actuator with active shunt control

Piezoelectric tube scanners are the actuators of choice in scanning probe microscopy. These nanopositioners exhibit a dominant first resonant mode that is excited due to harmonics of the input scan signal. This introduces errors in the scan obtained. The presence of this resonant mode limits the upper bound of a triangular scan rate to around 1/100th of the first mechanical resonance frequency. Passive and active shunts have shown to damp this resonant mode substantially and improve scan performance. Sensorless active shunts optimised using H₂ and H_infin techniques, is designed. These shunts reduce the amplitude of the first resonant peak of a prototype tube nanopositioner by 24 dB. A triangle wave input is used to test the improvement in scan performance due to the damping achieved by these active shunts. Analysis shows that damping the resonant mode in such fashion reduces the scan error by five times     

Active damping control of a high-power PWM current-source rectifier for line-current THD reduction

The use of active damping to reduce the total harmonic distortion (THD) of the line current for medium-voltage (2.3-7.2 kV) high-power pulsewidth-modulation (PWM) current-source rectifiers is investigated. The rectifier requires an LC filter connected at its input terminals, which constitutes an LC resonant mode. The lightly damped LC filter is prone to series and parallel resonances when tuned to a system harmonic either from the utility or from the PWM rectifier. These issues are traditionally addressed at the design stage by properly choosing the filter resonant frequency. This approach may result in a limited performance since the LC resonant frequency is a function of the power system impedance, which usually varies with power system operating conditions. In this paper, an active damping control method is proposed for the reduction in line current THD of high-power current-source rectifiers operating at a switching frequency of only 540 Hz. Two types of LC resonances are investigated: the parallel resonance excited by harmonic currents drawn by the rectifier and the series resonance caused by harmonic pollution in the source voltage. It is demonstrated through simulation and experiments that the proposed active damping control can effectively reduce the line-current THD caused by both parallel and series resonances.     

Broadband Frequency Invariant Beamformer

In the broadband signal processing, the array has different relative aperture for the different frequency bins, which results in waveform distortion. Moreover, the greater the bandwidth is, the more serious the distortion becomes. It is valuable to study the Frequency-invariant beam patterns (FIBPs) for receiving broadband signals without distortion. Based on the array dimensions, this paper will summarize some new methods to design a broadband beamformer with an FIBP. There will be two categories: One-dimensional arrays and Multi-dimensional arrays. For one-dimensional array, there are sampling rate method, minimax frequency invariant beamforming, etc. For multi-dimensional array, there are Bessel function method, Bessel function and phase mode method, and so on. Finally, we will discuss the pros and cons of every method.     

Optimum Coupling for Random Guides with Frequency-Dependent Coupling

We obtain exactly the covariance of the signal-signal and signal-spurious mode transfer functions of the coupled line equations with two forward-traveling modes, white random coupling with statistically independent successive values (e.g., white Gaussian or Poisson coupling), and a coupling coefficient that varies with the frequency of the signals on the line. No perturbation or other approximations are made in this work. Time-domain statistics for the corresponding impulse responses are obtained for moderate fractional bandwidths. These results are extensions of a similar treatment for frequency-independent coupling coefficients, given in a companion paper. If the coupling were independent of frequency, the signal distortion would ultimately decrease as the coupling increased, approaching zero as the coupling approached infinity. The frequency dependence of the coupling coefficient prevents the distortion from approaching zero; the optimum coupling, which achieves minimum signal distortion, is independent of guide length. Millimeter waveguides and optical fibers with random straightness deviations have coupling coefficients inversely proportional to the frequency. The above results yield the optimum random straightness deviation for such a guide. More forward modes can be treated in a straightforward way by more complicated calculations.     

微分相位校正电路的工作原理分析

微分相位失真是由传输系统的非线性引起的,它会造成彩色图像信号随亮度信号变化而引起色调失真,电视信号在传输的过程中总存在着非线性,它不仅会产生微分增益失真,同时还会产生微分相位失真、互调失真等,着重介绍的是微分相位失真。     

Surface Finish Effects on High-Speed Signal Degradation

In high-speed circuits, skin effects and dielectric properties are important factors for signal degradation considerations, especially in the microwave frequency region. When surface finishes are applied to prevent traces from oxidation, the electrical properties of traces are affected. In this work, experimental study and finite element method (FEM) based full wave simulation are used to investigate the effects of hot air solder leveling (HASL) and its alternatives on signal integrity. Classical interconnect structures, microstrip line, and differential mode coupled microstrip lines subjected to different finishes are investigated. Our work reveals that the net conductor loss that results from surface finishes is the dominant factor in signal degradation when the clock frequency is within the microwave frequency region. For microstrip line, the influence of surface finishes on signal distortion is negligible; for differential mode coupled microstrip lines, however, the surface finish effects, especially those with high resistivity, can lead to significant signal distortions. These findings are expected to have strong implications when designing high-speed circuits that meet strict timing requirements.     

Transmission Distortion in Multimode Random Waveguides

We consider the coupled line equations for two-mode random media in which both modes travel in the same (forward) direction as a model for multimode millimeter waveguides and optical fibers, in which mode conversion at imperfections occurs primarily in the forward direction. Some exact general properties satisfied by the transfer function and the impulse response of such a system are given for an arbitrary coupling coefficient. A random stationary coupling coefficient with statistically independent successive values, and consequently a white spectrum (e.g., a white Gaussian or a Poisson noise), permits exact determination of transmission statistics; we obtain first- and second-order statistics in the time and frequency domains. No perturbation or other approximations are made in any of the above results, which are obtained directly from the coupled line equations. These results are used to study signal distortion in long guides. By straightforward extension of this work more complicated calculations can treat more forward modes, but not backward modes or nonwhite coupling coefficient spectra. In this paper the coupling coefficient is assumed frequency independent, and under certain conditions the signal distortion decreases as the mode conversion increases. In practical cases the coupling coefficients are frequency dependent and the above behavior is modified; the present work is extended to this important case in a companion paper.