开口同轴探头去嵌入技术的研究

开口同轴探头测量技术,由于可实现非破坏性测试,一直是众多科学家及工程技术人员关注的焦点。但对于同轴探头的误差分析,研究不够深入。相位补偿技术是最常用的同轴探头去嵌入技术,该技术假设同轴探头是理想器件,忽略了同轴探头加工精度带来的误差。为此,提出了一种更为精确的去嵌入技术,即基于传输线模型的开口同轴探头去嵌入技术,通过实测得到表征同轴探头误差的校准参量,从而量化同轴探头的误差模型,以去除在测量中同轴探头带来的误差。介绍了该技术的基本原理,并与相位补偿技术进行了对比,最终通过实测验证了该技术是有效可行的。     

Elucidation of accuracy in calibration of MR signal intensity based on transmission amplitude method

To calibrate magnetic resonance (MR) signal intensity that depends on radio frequency (RF) coil loading, the transmission amplitude (TRA) for the excitation in the transmit-receive RF coil has been used as a good index in the so-called TRA method. As this TRA method needs neither an internal reference nor an additional external reference for the calibration, its accuracy is free from reference measurements. This study elucidated the calibration accuracy of MR signal intensities based on the TRA method. A cylindrical gel phantom was used for accuracy measurements with a 1.5-T MRI unit with conventional TI imaging as a simple pulse sequence for various loading conditions. The brain parenchyma of eight healthy volunteers also showed calibrated MR signal deviations. The error of the phantom calibration measurements was 2.18% (S.D.%). The background noise intensity of images was theoretically derived to correlate with the impedance mismatching of the RF coil, which is inevitable for fixed tuning, even for automatic tuning that is not always exact. Taking into account this noise intensity, the calibration method was modified to reduce its error to 1.50%. The standard deviations of the calibrated values in the thalamus and frontal white matter were 2.9 and 3.8%. respectively. We suggest that the modified TRA method is a practical and reliable technique to obtain clinical numeric evidence.     

Elucidation of accuracy in calibration of MR signal intensity based on transmission amplitude method

To calibrate magnetic resonance (MR) signal intensity that depends on radio frequency (RF) coil loading, the transmission amplitude (TRA) for the excitation in the transmit-receive RF coil has been used as a good index in the so-called TRA method. As this TRA method needs neither an internal reference nor an additional external reference for the calibration, its accuracy is free from reference measurements. This study elucidated the calibration accuracy of MR signal intensities based on the TRA method. A cylindrical gel phantom was used for accuracy measurements with a 1.5-T MRI unit with conventional T1 imaging as a simple pulse sequence for various loading conditions. The brain parenchyma of eight healthy volunteers also showed calibrated MR signal deviations. The error of the phantom calibration measurements was 2.18% (S.D.%). The background noise intensity of images was theoretically derived to correlate with the impedance mismatching of the RF coil, which is inevitable for fixed tuning, even for automatic tuning that is not always exact. Taking into account this noise intensity, the calibration method was modified to reduce its error to 1.50%. The standard deviations of the calibrated values in the thalamus and frontal white matter were 2.9 and 3.8%, respectively. We suggest that the modified TRA method is a practical and reliable technique to obtain clinical numeric evidence.     

硅基射频螺旋电感的在片测试和剥离方法

使用无锡上华0.5μm（DPTM）标准CMOS工艺制备了螺旋电感芯片,利用矢量网络分析仪和探针台搭建了硅基螺旋电感测试装置,对该硅基螺旋电感进行了测试。采用两种去除电路寄生参数的剥离方法,分析了高频条件下各种测试寄生参量的影响。建立了基于0.5μm（DPTM）标准CMOS工艺在片螺旋电感的寄生参量单π等效电路模型,详细列出了在片螺旋电感测试和寄生参数的剥离步骤,测试结果在0.1~8.5 GHz范围内与三维电磁场（HFSS）仿真结果有很好的一致性,验证了此方法在片上螺旋电感测试中的有效可行性。     

Channel Model and Measurement Methods for 10-kV Medium-Voltage Power Lines

Based on the typical topology and physical properties of a 10-kV power network, this paper first proposes a linear time-variant filter with additive noise to be the general channel model which takes into account the main problems that interfere with communications. Then it discusses the corresponding measurement methods. Next, for the first time in the related research area, the electrical loop wire was applied for the measurement of amplitude and phase responses of the transfer function H(f), which provides a better way to solve the problem of obtaining the phase response if the power line is relatively long. Also, the multitones method for the narrow-band fading measurement is put forward. Finally, it is concluded that moving the calibration reference plane of the network analyzer to a proper position improves the measurements efficiency and accuracy and these methods can be referred to in the 10-kV power-line channel study     

3GPP W-CDMA systems: design and testing

Newly emerging wireless signal formats can present significant design challenges to the system design engineer. Wideband code division multiple access (W-CDMA) can present many engineering design and verification challenges, due to its physical layer complexity as well as complexities that can arise when integrating RF and baseband designs to achieve a working system. System design engineers typically have the task of interpreting standards specifications, first for partitioning subsystem requirements, then verifying that the end-to-end system design (typically including both baseband and RF designs) will meet specifications when they are finally integrated. This article considers a case study that illustrates the importance of simulating baseband and RF designs together to accomplish this task. Specifically, a conceptual system design that includes system models, a fixed-point finite impulse response filter, and transistor-level circuit design is simulated and verified together against measurements defined in the third-generation partnership project (3GPP) W-CDMA standards specifications. Tradeoffs between improving either the RF or baseband design to meet overall system specifications will be discussed. Finally, design verification using "connected solutions," or connectivity between, electronic design automation software and test equipment will be described, illustrating how verification testing can be started earlier to help reduce risk by identifying performance issues early in the design cycle, when they are potentially easier and costly to implement     

矢量网络分析仪未知直通校准技术及应用

随着现代电子信息技术的发展,如何提升各种微波非插入器部件的网络特性测量精度是长期以来工程师面临的挑战之一。矢量网络分析仪未知直通校准技术采用SOLT校准和TRL校准相结合的方法,实现了非插入器件直接在校准面进行高精度测量。简要对比了传统测试方法优缺点,给出未知直通校准模型、校准过程和具体技术应用。实验结果表明,该技术能够很好地解决未知直通部件S参数测量难题,可以去除传统方法中使用外加适配器引入的各项测量误差,并且不要求校准直通件特性已知,可有效提高测试精度并具有极大应用灵活性。     

数字化电能表基本误差试验方法研究

随着智能变电站的快速发展,数字化电能表取代传统电子式电能表是一种必然趋势。针对当前数字化电能表基本误差试验方法不够成熟、测试效率低下的情况,分析了国家标准及国家电网公司企业标准给出的几种基本误差试验方法:标准数字表法、标准数字源法、标准模拟表法、瓦秒法,研究了这些方法的测量准确度与校验实时性的关系,并给出了相应的提高测量准确度或缩短校验时间的措施,以便于在不同工况下选取适当的数字化电能表校验方案,为数字化电能表基本误差试验方法向标准化、体系化、专业化发展提供技术参考。     

A new technique to measure the thermal resistance of LDMOS transistors

This paper introduces a new dc technique for the extraction of the thermal resistance of LDMOS transistors. The new extraction method has distinctive advantages over existing techniques: 1) it is based on dc measurements of the I-V output curves at different ambient temperatures, thus requiring only very standard and inexpensive equipment, with the exception of a stable and accurate temperature control; 2) it does not need any special layout or test structure, nor any knowledge of the physical structure of the device under test; and 3) it can be applied to both packaged and on-wafer FETs. We applied the new technique to LDMOS transistors with a wide range of gate widths, namely, 2.68-84.42 mm, obtaining well-behaved and consistent results. A comparison of the new method with a standard extraction technique based on short-pulse measurements at different ambient temperatures showed substantial agreement between the two.     

微波射频差分探针去嵌入理论研究

为了获得被测件(DUT)准确的散射参数(S参数),研究了用于差分网络的去嵌入理论。在经典的差分探针结构的基础上,提出了一种可以抑制差分测试中共模信号影响的新型差分探针模型,即信号-信号探针(SS探针)。并完成了直通-反射-传输线(TRL)校准件和DUT的设计,推导了差分网络的多模去嵌入理论,编写算法并利用测试数据进行计算,仿真与测试结果表明在0~8 GHz的频率范围内,去嵌入后的散射参数的幅度、相位与仿真结果一致性较好。     

基于激光感生击穿光谱的燃煤结渣特性评估

提出一种利用激光感生光谱在线测量技术来评估燃煤结渣特性的方法。根据测量机理搭建了实验台架，选取4种典型的燃煤作为分析样品，其中6种用于制定激光感生击穿光谱定量分析的标准曲线，并利用该曲线对另外两种样品进行分析测量，将测量结果进行化学换算计算出煤粉的硅铝比以评估煤粉的结渣特性。将评估结果与以实验灰分分析为基础的其他结渣特性预测指标的计算结果进行了比较，结果表明两种预测结果相符。同时，文中也对进一步提高该方法预测精度的测量系统改进方案进行了探讨。     

A study of radar cross-section measurements in an anechoic chamber

Radar cross-section measurement techniques in a relatively small anechoic chamber are discussed in this paper. The proper configuration of the measurement system and antenna/target setting for securing a wide dynamic measurement range is studied. A quasi-monostatic configuration is recommended here instead of a monostatic one, and various suggestions are made for reducing isolation error and background noise, along with calibration techniques and antenna settings. Measurement examples are shown for a conducting plate and parallel plane waveguide cavities. These results are then compared with those derived theoretically by the geometrical theory of diffraction and the Wiener-Hopf technique. Good agreement is obtained between them, and the validity of our measurements is confirmed. © 1998 Scripta Technica, Electr Eng Jpn, 123(1): 8–14, 1998     

非插入式器件的测量

利用矢量网络分析仪测试射频微波器件时,经常需要对非插入式器件进行测量,去除适配器的影响。介绍了一种去除适配器影响的测量方法,通过单端口测试未知特性的转接器,根据假设条件和算法,使级联后理论计算值接近实际测量值,进而确定转接器的真实值,最终得到被测件的准确值,并且验证得到正确的实验结果,从而去除转接器在测试中对被测件的影响。为进一步展开端口延伸和去嵌入技术的研究奠定理论基础。     

The Sampling Oscilloscope as a Microwave Instrument

Most of the equipment required is readily available in most microwave labs: a vector network analyzer, a microwave signal generator, and, of course, a sampling oscilloscope. In this paper, the authors summarize many of the corrections discussed in " Terminology for high-speed sampling-oscilloscope calibration" [Williams et al., 2006] and "Magnitude and phase calibrations for RF, microwave, and high-speed digital signal measurements" [Remley and Hale, 2007] that are necessary for metrology-grade measurements and Illustrate the application of these oscilloscopes to the characterization of microwave signals.     

基于光学传感的交直流混合场一体化测量实现

针对交、直流混合场测量的问题,文中基于电光晶体Pockels效应设计了旋转式光学传感元件,该设计不仅适用于测量交直流混合场,而且抑制了测量中的波动和误差。分别推导了旋转式光学电场传感器测量直流电场、交流电场以及混合场时的传感原理。为了区分不同频率下的电场强度,将Hilbert-Huang时频变换技术应用到光学电场测量,并且给出不同频率下的测量方案。在光学一体化传感器标定后,对混合场进行测量,实验数据表明,所提出的光学电场一体化测量机制适用于准确地测量交、直流混合场。     

A simple CAD-based method to develop and evaluate calibration standards

The vector network analyzer (VNA) is one of the tools most commonly used by microwave engineers for component characterization and modeling. It allows the reflection and transmission coefficients to be quickly and efficiently measured. With any VNA measurement, it is important for the engineer to know and understand the error associated with a measurement. A key component of this measurement error comes from the quality of the VNA calibration. In this article, we review the fundamentals of VNA calibration and the 12-term error model. We outline the basic short-open-load-through (SOLT) calibration technique and a simple computer-aided design (CAD)-driven program to aid in the extraction and evaluation of SOLT calibration coefficients. The CAD-driven technique is useful because it allows calibration accuracy to be efficiently evaluated over frequency. It also allows for the systematic evaluation of process variation effects on the accuracy of on-wafer-calibration (OWC).     

高压大功率IGBT器件温度系数校准方法研究

结温的准确测量对于功率IGBT器件状态监测和可靠性评估具有重要意义,小电流下饱和压降法作为使用最广泛的结温测量方法被各类测试标准推荐使用,温度系数校准是使用该方法的第一步,也是结温测量的基础.传统的温度系数校准方法对于高压大功率IGBT器件存在适用性和准确性的问题.首先,深入讨论和对比了目前常用的2种温度系数校准系统的...     

New practices for partial discharge detection and localization in large rotating machines

This paper presents a new technique for detection and localization of partial discharges (PD) in large rotating machines. In this technique, denoted "InTech", a stator winding with (n) coils is equipped with (n + 1) inductive sensors; as a result, every stator coil is situated between two sensors. The measurement is then focused on the individual stator coils. In this way common difficulties facing partial discharge measurements in rotating machines such as attenuation and distortion of the signals in the stator winding, noise reduction, and the calibration accuracy are reduced considerably. The treatment of the sensor signals, using a special method, results in a measurement of PD in each respective stator coil. In addition, the stator coil from which the PD originates is identified. Results from field measurements on both hydro and turbo machines are presented and discussed.     

同步相量测量装置校准器参考相量计算方法

电力电子设备的广泛应用导致电力系统逐渐出现了新的稳定性与可靠性问题,亟需高精度实时测量与感知技术,为解决上述问题提供数据基础。作为最有效的动态监测手段之一,同步相量测量装置(PMU)的测量精度至关重要。提出了一种PMU校准器的参考相量计算方法,为PMU测试提供校准参考值。该方法分析了电力系统典型静动态信号特性,建立了基波相量通用信号拟合模型,可表征PMU测试标准中除阶跃测试外的所有静动态测试信号。提出了基于非线性拟合的相量幅值、相角与频率迭代求解方法,并根据所得频率提出了基于最小二乘法的频率变化率计算方法。进一步,分析揭示了迭代初始值、计算时间窗长和拟合阶数对计算精度的影响及其设置方法。仿真与实验测试结果表明,该方法精度至少比标准规定的精度要求高1个数量级,可用于PMU的测试与校准。     

计量设备常规期间核查探讨

期间核查是实验室保证计量标准和仪器检定、校准状态可靠的重要手段。介绍了期间核查的概念、期间核查的对象、核查方法以及期间核查工作的实施,介绍了针对不同的核查对象采用合适有效的核查方法,为实验室开展期间核查工作提供了技术参考。