Measuring Volterra Kernels of Analog-to-Digital Converters Using a Stepped Three-Tone Scan

The Volterra theory can be used to mathematically model nonlinear dynamic components such as analog-to-digital converters (ADCs). This paper describes how frequency-domain Volterra kernels of an ADC are determined from measurements. The elements of the Volterra theory are given, and practical issues are considered, such as methods for signal conditioning and finding the appropriate test signals scenario and suitable sampling frequency. The results show that, for the used pipeline ADC, the frequency dependence is significantly stronger for second-order difference products than for sum products and the linear frequency dependence was not as pronounced as that of the second-order Volterra kernel. It is suggested that the Volterra kernels have the symmetry properties of a specific box model, namely, the parallel Hammerstein system.     

Device Verification Testing of High-Speed Analog-to-Digital Converters in Satellite Communication Systems

This paper presents a step-by-step sequence of operations for the dynamic performance testing of a high-speed analog-to-digital converter (ADC) using on-chip digital demultiplexing and clock distribution. Demultiplexed digital outputs are postprocessed and fed into a computer-aided ADC performance characterization tool. The described methodology reduces test costs and overcomes many test hardware limitations. The problems of high-sampling-rate ADC testing are described. As our focus is on RF communication system applications, we emphasize the measurement of intermodulation distortion (IMD) and effective resolution bandwidth (ERB). Accurate gain and phase matching are also of critical importance. As Fourier analysis is an important component of characterization, we address the issue of automated sample window adjustment to eliminate leakage and false spur generation. A 6-bit 800 MSample/s dual-channel SiGe-based ADC is used as a target example.     

微电子封装中聚合物磁性材料的研制

将不同量的纳米三氧化二铁在分散剂等条件下与自制的聚酰亚胺复合,制成聚酰亚胺/纳米氧化铁复合材料,采用古埃法(Gouy's)、红外光谱(FTIR)、吸水性能测试、拉伸强度测试等手段,表征了材料的结构及特有的超顺磁性。结果表明,这种复合材料具有超顺磁性,而纯聚酰亚胺不具备,吸水率下降,拉伸强度好。     

Use of Digital-to-Analog Converters in Circuit Design

High-quality digital-to-analog converters are now available at relatively low prices and can be used to advantage in many instrumentation applications. The examples that are considered in this paper include a very general transducer output linearizing analog-to-digital converter, an analog multiplier and a more general signal processing circuit that has an output E0 of the form E0 = KEs1f(Es2) where K is a constant, Es1 and Es2 are input voltages and f(Es2) is any prescribed function of Es2.     

Estimate of the Average Power of Signals with Fluctuations in the Phases of the Components of Harmonic Oscillations with Aperture Uncertainty of an Analog-to-Digital Converter

Measurement Techniques - Results are presented from studies of the estimation of the average power of signals with phase fluctuations of the components of harmonic oscillations. These studies take...     

Abrasive Powder Materials with Wear-Resistant and Magnetic Components

Inorganic Materials - TiC–Fe based powder materials have been prepared by a self-propagating high temperature synthesis comminution process. The type of deforming device (cone or mill cutter)...     

InSb磁敏电阻角位移传感器的研究

简单分析了InSb磁敏电阻的工作原理,讨论了利用偏置磁场作用于半桥磁敏电阻构成转动速度及位移传感器的测试原理;针对半导体材料对温度十分敏感的特点,提出了利用浮动零点跟踪技术测试齿轮转速的方法,并对其优缺点进行了讨论。     

A Novel Displacement Transducer Using the Second-Harmonic Type of Magnetic Modulator

A novel displacement transducer using the secondharmonic type of magnetic modulator is proposed to detect a static displacement as low as 0.1 ?m. The operation of transducer is based on modulating and amplifying the magnetizing force proportional to the input displacement by means of the second-harmonic type of magnetic modulator. In order to enhance signal sensitivity, 4 pole-pieces type dc bridge and differential type moving detector are used for modulation circuit of this transducer.     

Noise-Enhanced Measurement of Weak Doublet Spectra with a Fourier-Transform Spectrometer and a 1-Bit Analog-to-Digital Converter

We demonstrate an efficient noise dithering procedure for measuring the power spectrum of a weak spectral doublet with a Fourier-transform spectrometer in which the subthreshold interferogram is measured by a 1-bit analog-to-digital converter without oversampling. In the absence of noise, no information is obtained regarding the doublet spectrum because the modulation term s(x) of its interferogram is below the instrumental detection limit B, i.e., |s(x)| < B, for all path difference x values. Extensive numerical experiments are carried out concerning the recovery of the doublet power spectrum that is represented by s(x) = (s(0)/2)exp(-pi(2)x(2)/beta)[cos(2pif(1)x) + cos(2pif(2)x)], where s(0) is a constant, beta is the linewidth factor, and ?f? = (f(1) + f(2))/2. Different values of ?f?, s(0), and beta are considered to evaluate thoroughly the accuracy of the procedure to determine the unknown values of f(1) and f(2), the spectral linewidth, and the peak values of the spectral profiles. Our experiments show that, even for short observation times, the resonant frequencies of s(x) could be located with high accuracy over a wide range of ?f? and beta values. Signal-to-noise ratios as high as 50 are also gained for the recovered power spectra. The performance of the procedure is also analyzed with respect to another method that recovers the amplitude values of s(x) directly.     

Prediction of the Magnetic Variation Field Based on Multiple Geomagnetic Components

A new method for the prediction of the geomagnetic variation time series based on multiple geomagnetic components is presented in this paper. The method used the data of multiple geomagnetic components (H, D, Z) with different kinds of combination (H, Z; H, D; H, D, Z) from a series of geomagnetic stations to predict the Z component (both in single-step prediction and multi-steps prediction). The comparison and analysis between the new method and the method based on single Z component are done in the paper. The results indicate that the new prediction method based on components (Z, H) has a higher precision than the model based on single Z component.     

Oil Displacement from a Porous Medium with the Aid of a Graphite Suspension

It has been found that N aqueous suspension of planar graphite nanoparticles exhibits properties of displacement fluid at the oil–water interface. Experiments with the Hele–Shaw cell showed that the process of oil displacement from the interface is not accompanied by the formation of viscous “fingers” as a result of development of instability at the oil–water interface.     

Displacement of bodies with tossing on a vibrating surface

A new approach to investigations of structural mechanisms that accomplish displacement of bodies with tossing on a vibrating surface is suggested that explains some facts that are widely known from experiments. This approach makes it possible to select criteria for optimization of the geometric parameters and physical charactersitics of the objects created that provide a reduction in mechanism loading and economy in energy resources.     

The Change in the Components of the Complex Magnetic Permeability of Nonuniformly Magnetized Ferromagnetic Rods

The results of experimental investigations of demagnetizing and surface effects in extended ferromagnetic rods, magnetized by the alternating magnetic field of coils of different length in the 20 Hz – 50 kHz frequency band are presented. A physically justified explanation of the fact that the components of the complex magnetic permeability are independent of the length of the coil at the higher frequencies of this band is given.     

铁磁构件磁记忆检测技术的研究进展

金属磁记忆技术在检测铁磁构件应力集中和疲劳损伤等早期失效方面具有潜力.从磁记忆效应的机理研究、基础性试验探讨到检测信号的影响因素分析以及工程应用,对该技术在近几年来的发展现状进行了综述,并讨论了其在理论和实际应用中存在的问题.在国内外现有研究的基础上,指出了磁记忆检测技术的特点和需要进一步研究的发展方向.