Clock feedthrough compensation with phase slope control in SCcircuits

A clock feedthrough compensation technique for SC circuits is presented. The principle is based on the control of the switch turn-off slope. A single control block can drive a large number of identical SC structures, thus minimising area overhead. Experimental results from an integrated prototype show that the injected charge is reduced by a factor as high as 13     

On the relationship between PSRR and clock feedthrough in SCfilters

A novel linearized model for calculating the power supply rejection ratio (PSRR) of switched-capacitor (SC) circuits due to switch charge injection (clock feedthrough) is presented. The inclusion of clock feedthrough accounts for the low-frequency PSRR degradation not modeled by other methods. This is particularly important in high-frequency SC circuits, as is confirmed by simulation and measurement results. The model defines a useful link between transient clock feedthrough analysis and effective coupling capacitor models that are suited for AC analysis. The abstraction of differentiating an injected charge with respect to voltage to get effective coupling capacitors leads to efficient analysis techniques, since clock delays and elaborate device models can be considered once at the outset, and then dispensed with in favor of simpler device elements. This makes the model more suitable for hand calculations and analysis with standard SC simulation packages     

具有温度补偿功能的等应变梁双FBG真空静电电压传感器

为了实现高电压的精确测量,提出了一种具有温 度补偿功能的光纤布拉格光栅(FBG)真空静电电压 传感器。基于所设计的真空静电传感器 构建了高压静电电压传感实验系统,实现了静电电压的精确测量;同时,利用参数一致的双 FBG结构方案,实现 了传感器的温度补偿功能。实验结果表明:本文传感器可实现5～39 kV直流高压和交流高压有效值的测量,并且 能够达到较高的精度,5～12 kV的计算精度为1.25%,12～39kV的计算精度为0.55%,传感 曲线的拟合度为 0.99976。本文构建的系统,抗干扰能力强、精度高和 稳定性好。     

Identification and compensation of torque ripple in high-precisionpermanent magnet motor drives

Permanent magnet synchronous machines generate parasitic torque pulsations owing to distortion of the stator flux linkage distribution, variable magnetic reluctance at the stator slots, and secondary phenomena. The consequences are speed oscillations which, although small in magnitude, deteriorate the performance of the drive in demanding applications. The parasitic effects are analyzed and modeled using the complex state-variable approach. A fast current control system is employed to produce high-frequency electromagnetic torque components for compensation. A self-commissioning scheme is described which identifies the machine parameters, particularly the torque ripple functions which depend on the angular position of the rotor. Variations of permanent magnet flux density with temperature are compensated by on-line adaptation. The algorithms for adaptation and control are implemented in a standard microcontroller system without additional hardware. The effectiveness of the adaptive torque ripple compensation is demonstrated by experiments     

Measurement and modeling of charge feedthrough in n-channel MOS analog switches

Charge feedthrough in analog MOS switches has been measured. The dependence of the feedthrough voltage on the input and tub voltages, device dimensions, and load capacitances was characterized. Most importantly, it was observed that the feedthrough voltage decreases linearly with the input voltage. The significance of this observation when considering harmonic distortion in sample-and-hold circuits is discussed. A first-order computer simulation based on the quasi-static small-signal MOSFET capacitances shows good agreement with experimental results.     

Sensing characteristics of an electrostatic recording camera

The electrostatic recording camera can store a large number of pictures and provide for television transmission of these pictures at arbitrary times following optical exposure. This paper describes analytically the operation and performance of an electrostatic recording camera developed especially for use in observation satellites. The device is seen to have comparable signal-to-noise ratio and sensitivity to those characteristics of a vidicon. Camera resolution is also shown to depend mainly on the readout electron beam.     

The fabrication of an electrostatic linear actuator by siliconmicromachining

A microactuator consisting of a plane wafer with striped electrodes covered with an insulation layer and thin cylindrical rollers was designed. When voltage is applied between the striped electrodes and the roller, the electric field between them attracts the roller, causing it to roll. As the roller passes over a striped electrode, the electrode is discharged and another in the forward direction is charged to keep the movement. The electrostatic linear actuator (ESLAC) consists of rollers inserted between a C-shaped stator and a slider that displaces linearly. Silicon micromachining techniques such as lithography, PCVD, and etching were utilized to fabricate the plane wafer. Model actuators were realized on silicon wafers. The performance of the models is examined     

Positioning performance and straightness error compensation of the magnetic levitation stage supported by the linear magnetic bearing

This paper reports high-precision motion control at the target position and the offline compensation of the straightness error occurring during the motion of the magnetically levitated stage supported by the linear magnetic bearing. The linear magnetic bearing is composed of electromagnets and sensors in the same module to enable easy maintenance and to reduce the machining error, and the conventional linear quadratic Gaussian control is adopted for the motion control of the stage. The test results show that the stage can compensate the straightness error precisely, so that it is expected that this stage can be applied to high-precision linear motion applications.     

Propagation velocity of whistler-mode signals in an unstable and abnormally dispersive plasma-beam system

A propagation velocity of a whistler-mode signal in an unstable and abnormally dispersive plasma-beam system was investigated. Responses of the plasma in real time and space were computed by the inverse Fourier-Laplace transformation. The computed results of the propagation velocity are compared with various velocities analytically determined from the dispersion equation.     

Frequency control and chirp compensation from an electro-opticalDBR laser

The variability of optical frequency modulation with electric field in an electro-optical phase section is analysed. When configured for maximum sensitivity, the electro-optical phase section was used to compensate for the chirp of the gain section: 48 ps and 8.5 GHz wide transform-limited pulses were obtained at 5 GHz     

静电摇摆器自由电子激光的自发辐射

基于静电摇摆器中电势场的一种典型二维模型 ,在小振幅振动情况下讨论了相对论电子束在其中的运动规律 ,计算得到了该类型自由电子激光的自发辐射谱。上述结果与平面磁摇摆器有类似的形式     

Study of solar cell fabrication using an electrostatic thick-filmprinting method

A novel thick-film circuit printing technique which is based on the electrostatic principle known as noncontact electrostatic thick-film printing was developed for the metallization of edge-defined film-fed growth (EFG) solar cells. The conventional thick-film solar cell inks were modified by adding 10-20% terpineol solvent. The effects of ink viscosity, applied voltages, nozzle diameter, and nozzle-to-substrate distance on line definition and ink-flow rate were investigated. A simple theoretical model was derived for the electrostatic ink ejection. The minimum line width obtained was 3 mm. Multilayer printing was able to be used to raise the line film thickness. The maximum line width obtained was about 20-30 mm for a single run. The system is now completely computercontrolled and capable of printing films onto solar cell substrates reliably, with a high degree of accuracy. Multiple-layer prints can be made with food layer-to-layer registration     

Modeling and measurement approaches for electrostatic discharge in semiconductor devices and ICs: an overview

Electrostatic charges can be generated everywhere. When they are discharged through semiconductor devices and integrated circuits, an event called an electrostatic discharge (ESD), failure of electronics systems using these devices and ICs can occur. This paper first gives an overview of the ESD sources and models. Then the emphasis is placed on the modeling and measurements of the most commonly used of these models called the human body model (HBM). Various HBM protection circuits are examined to look at ways of preventing ICs from being damaged should ESD events occur. The issue of HBM measurements is also addressed so that the rapid transient associated with this ESD model can be accurately measured and characterized.     

荧光LED通信系统线性失真测量及其补偿

为了改善线性失真对荧光LED通信系统性能的影 响,首先建立了通信实验系统, 采用网络分析仪测量了通信系统的幅频响应,分析了线性失真特性。根据通信系统线性失真 的测量结果,设计了一、二、三阶高通滤波器作为线性失真补偿电路,将其与荧光LED通 信系统级联,分别测量了级联后系统的幅频响应。结果显示,采用三阶补偿电路后,荧光 LED通信系统的线性失真得到了明显改善,系统增益的衰减幅度由补偿前的50dB(0.3~6MHz)降低为三阶补偿后的20dB(0.3~45MHz)。为了确保通信系统具有相对平坦的增益 特性且要求系统增益的波动小于10dB时,系统的通频带宽度可从补 偿前的1.8MHz提高到 三阶补偿后的41MHz (范围为3~44MHz),增 大了约23倍,且在此频带范围内,系统具有 相对较大的增益(约为－30dB)。因此,补偿荧光LED通信系统的线 性失真,可以很好扩展通信系统所需的通频带宽度。本文的实验和分析可为进一步优化系 统参数及改进通信性能提供参考依据。     

Equations of motion for a free-electron laser with an electromagnetic pump field and an axial electrostatic field

The equations of motion for a free-electron laser (FEL) with an electromagnetic pump field and a static axial electric field are derived using a Hamiltonian formalism. Equations governing the energy transfer between the electron beam and each of the electromagnetic fields are given, and the phase shift for each of the electromagnetic fields is derived from a linearized Maxwell wave equation. The relation between the static axial electric field and the resonant phase is given. Laser gain and the fraction of the electron energy converted to photon energy are determined using a simplified resonant particle model. These results are compared to those of a more exact particle simulation code.     

不稳定腔的频谱分析(续)

一、具有非均匀介质不稳定腔的频谱分析 根据[1]可知,光在不稳定腔中的振荡可以等效于在一个透镜序列中的传输问题来进行处理。具有非均匀介质的不稳定腔也可以用这样的方法来处理,所不同的是把[1]中的光阑函数     

Thermophysical properties of molten refractory metals measured by an electrostatic levitator

Thermophysical property measurements of molten refractory metals, which are very difficult and hardly conducted with conventional methods due to their high melting temperature and risk of reaction with container walls, have been conducted using noncontact diagnostic techniques in an electrostatic levitator. This paper first briefly summarizes the procedures and methods adopted by the Japan Aerospace Exploration Agency to enable the measurements of density, surface tension, and viscosity on molten refractory metals. Typical data of superheated and undercooled liquids that would have been impossible to obtain without the use of these techniques are then reported. Specifically, density, surface tension, and viscosity of Ti, Zr, Nb, Mo, Ta, and W were successfully measured over a wide temperature range, including the undercooled region.