Colliding pulse phase detector for picosecond resolution timing measurement

A phase detector consisting of Schottky diode peak detector taps distributed along an integrated GaAs transmission line has been fabricated. Pulses counterpropagate on the line, forward biasing taps in the region of pulse overlap. The relative phase gain, determined from the captured overlap function, is 20 mV/ps.<>     

天空光辐射亮度测量系统定标及数据分析

随着辐射测量技术的不断发展,测量设备的精度越来越被关注,而对设备准确定标是提高测量设备精度的重要保证.详细介绍了利用标准光谱辐射计实现天空光辐射亮度测量系统的实验室绝对辐射定标方法和利用汞灯实现天空光辐射亮度测量系统的波长定标方法,并采用前述方法对TKFS01型天空光辐射亮度测量系统进行了定标,给出了定标的不确定度.通...     

High-frequency periodic time-domain waveform measurement system

A system is presented for the accurate measurement of high-frequency periodic time-domain voltage and current waveforms of a nonlinear microwave device. The measurements are performed in the time domain using a high-speed sampling oscilloscope. The results are Fourier-transformed into the frequency domain for error correction and then back into the time domain. An error-correction algorithm is presented that makes it possible to obtain accurate waveforms in spite of nonideal system components. Practical difficulties in measurement-system characterization are also discussed. An accurate circuit model for the measurement fixture is developed and its element values are determined. Measurement results are given showing the waveforms in a microwave transistor operated in the nonlinear region. The errors caused by signal processing are discussed     

Calibration and measurement of a wideband six-port polarimetricmeasurement system

The principle of operation, calibration procedure, and experimental results of a wideband six-port polarimetric measurement system are described in this paper. This measurement system can measure the polarization states of incoming waves and the polarimetric scattering matrices of scattering targets from the wideband power data. The imbalances and coupling between antenna polarization channels and the characteristics of microwave components used in the measurement system are calibrated using three partly unknown scattering calibrators that are illuminated by four unknown-polarized calibrating waves     

用半导体激光器实现50KV脉冲波形安全测量方法的研究

一种可确保人身和设备安全的高压脉冲波形的测量方法。它由发送电路将被测电压或电流之实时值转换成串行数字信号,再用它调制半导体激光器发出的光,其湛我穿过100mm以上变压器油和10mm厚玻璃板,送给接收电路。后者将串行数字信号转换成模拟信号,然后送给示波器,即可观察到被测高压脉冲电路电压或电流的波形。所述方法新颖实用,具有参考价值。     

20 GHz on-chip measurement of ESD waveform for system level analysis

Reliability of embedded electronic products is a challenging issue regarding ElectroStatic Discharge (ESD) events into real live applications. This is strongly related to the increased number of embedded systems and to technologies shrinking that result in less robust chips. To ensure the safety of electronic systems, the ESD events have to be taken into account at first design phase. But equipment manufacturers are facing the dilemma that no information is provided by the semiconductor manufacturers. At the same time Integrated Circuit (IC) designers have to take into account the final application environment to build the ESD protection strategy. Depending on the external components (external means around the chip) the on-chip current path could change. Understanding how the system environment impacts the current path within the chip is needed. This paper deals with on-chip oscilloscope developed for in-situ measurement of real ESD event in 65 nm CMOS technology. The measurement bandwidth of the embedded sampler is 100 GHz, and 20 GHz for the probes. Thanks to this technique, impact of the system on the current path of the on-chip ESD strategy will be observed. Some measurement results during an ESD stress on an I/O structure will be presented and analyzed showing that PCB trace and package induce the creation of new current paths.     

All-electronic free-space picosecond pulse generation and detection

An all-electronic system for generating, propagating and detecting picosecond electromagnetic pulses using monolithic integrated circuits is described. With a 1.8 ps (10%-90%) nonlinear transmission line step generator driving a monopole antenna for transmission and a similar antenna driving a diode sampler for reception, the system has shown spectral coverage from 90 to 170 GHz.<>     

Improved Raman-fibre pulse delay measurement system

An improved design for pulse delay measurements using a Raman generating fibre pumped by a Nd:YAG laser has been realised. The reproducibility error in the measured delay times is only 2 ps RMS, because of strongly reduced jitter, compensation of long-term instability and prevention of irregularities in the shape of the pulses.     

基于小波分析的不对称脉冲信号波形研究

不对称脉冲轨道电路设备产生的不对称脉冲信号,在传输中由于轨道分路不良和干扰等出现失真,这就需要研究一种更为准确、可靠和抗干扰性能好的检测方法来完成对信号的实时分析与检测。基于小波分析的不对称脉冲信号波形检测,利用小波变换模极大值特性,可以有效地解决这个问题。结果表明,该方法有较强的适用性,算法简单,运算速度快。     

Analysis of picosecond pulse shape synthesis by spectral masking in a grating pulse compressor

This paper analyzes the synthesis of arbitrarily shaped optical pulses by spectral filtering in a fiber-and-grating pulse compressor. Spectral filtering of phase and amplitude is achieved by masking the spatially dispersed frequency components within the compressor. We show that the spectral filter is the convolution of the mask with the beam's transverse intensity profile. We discuss the effect of diffraction from the features of the physical mask, and show how finite spatial resolution limits the range of attainable temporal profiles. The fundamental limitation on spectral resolution is derived. Spectra and temporal pulse shapes corresponding to a variety of physical masks are calculated and are found to be in excellent agreement with experiments done with compressed pulses from a mode-locked Nd: YAG laser.     

电子测量误差分析研究

人们的生活会受到电子测量的结果影响,由于测量的过程难免受到多种因素的干扰,电子测量的结果会存在误差,本文从电子测量误差的概念出发,分析了造成测量误差的原因,并提出了消除电子测量误差的方法。     

Error-corrected large-signal waveform measurement system combiningnetwork analyzer and sampling oscilloscope capabilities

A large-signal automatic stepped CW waveform measurement system for nonlinear device characterization is presented that combines the high accuracy of a vector network analyzer with the waveform measurement capabilities of a sampling oscilloscope. A large-signal error model and a corresponding coaxial calibration procedure are proposed to describe the systematic errors of the measurement setup. The error parameters and the correction algorithm are independent of the properties of the RF generator. System accuracy is investigated by Schottky diode verification measurements with different offsets from the reference plane. GaAs MESFET reflection and transmission response measurements with error correction extended to the planar device under test (DUT) reference planes are given     

Electrostrictive self-focusing of picosecond laser pulse trains

A nanosecond-long train of picosecond laser pulses theoretically can produce self-focusing by electrostriction, even though the trapping threshold for a single picosecond pulse is very high. The relative roles of electrostriction and various types of Kerr effect in picosecond pulse train self-focusing should be assessed.     

A novel noninvasive measurement technique for analyzing the pressure pulse waveform of the radial artery

Previous noninvasive measurements of the pulse waveform of the radial artery have not employed standard positioning procedures. Here, we propose a new noninvasive measuring apparatus that has a two-axis mechanism and employs a standard positioning procedure for detecting the optimal site for accurately measuring the pressure pulse waveform (PPW). A modified sensor was designed to simultaneously measure the arterial diameter changed waveform (ADCW) and PPW. Considering the artery as a cylinder, the measured waveform would be distorted if the sensor were not at the middle of arterial width. Moreover, a blood vessel is elastic, and its compliance changes with the transmural pressure, being maximal when the transmural pressure is equal to zero. The sensor should detect the PPW with the lowest possible distortion and, hence, an analysis of the vascular geometry and an arterial model were used to design a standard positioning procedure based on the ADCW for the X and Z axes. In order to verify the resolution of the X axis scanning procedure, the echo method was used to measure the radial artery outer diameter in ten healthy subjects. The difference between the scanning width and the actual arterial diameter was 0.36 +/- 0.23 mm (mean +/- SD). Finally, the PPW as measured at the optimal position was used to diagnose myocardial ischemia symptoms in 60 elderly subjects whose chief complaint was chest pain, with the exercise electrocardiogram being used as a reference to compare between individuals with and without myocardial ischemia. The PPW analysis used the harmonic components in the frequency domain. We found that the fourth harmonic of the Fourier series differed significantly between the groups (p = 0.0039), which is consistent with previous studies. The results indicate that our noninvasive measurement apparatus is very suitable for analyzing the PPW of the radial artery.     

多自由度运动误差在线测量系统设计

针对传统多自由度运动误差测量系统一直存在易受工作环境影响,误差测量稳定性差的问题,提出并设计基于激光干涉仪的多自由度运动误差在线测量系统。通过分析激光干涉仪误差测量原理,在传统运动误差测量系统中引入激光干涉仪,利用激光干涉现象对多自由度运动物体精确测定,建立多自由度运动误差在线测量数学模型,实现多自由度运动误差的测量。实验结果表明,相比传统测量系统,改进设计的多自由度运动误差在线测量系统,具有良好的抗干扰能力及较高的测量准确性。     

大口径中波红外辐射特性测量系统标定

文中设计采用面源黑体对大口径中波红外辐射特性测量系统进行辐射标定,通过改变探测器积分时间的方式提高系统红外辐射强度测量的动态范围,得到全系统基于积分时间变量的辐射标定公式.分析了探测器像元的饱和特性,得到了像元的饱和边界条件.边缘像元的动态范围相对于中心像元扩大近50％.在1-3 ms积分时间范围内,探测器像元响应灰度...     

Phase compensation and waveform reshaping of picosecond electricalpulses using dispersive microwave transmission lines

The phase compensation effect of microwave transmission line dispersion is studied and a simple effective method for reshaping and compressing picosecond electrical pulses generated from photoconductive switches is proposed. It is shown that a piece of a dispersive strip transmission line can be used as a phase equalizer to compensate the phase distortion included in asymmetric pulses, resulting in effective reshaping and compression of these ultrashort pulses. Initial design formulas of the strip transmission lines for this purpose are presented, together with computer simulation results which confirm the theoretical predictions. Experimental results are presented to show the substantial pulse reshaping effect. A comparison between theory and measurement is given     

Calibration of wide-band polarimetric measurement system usingthree perfectly polarization-isolated calibrators

An improved calibration method for a wideband polarimetric measurement system using three partly unknown, perfectly polarization-isolated calibrators is presented, with experimental results measured from 7 to 17 GHz. The cross-polarized information is provided by rotating the third calibrator to an arbitrary angle with respect to the radar range direction. Only the copolarization terms in the polarimetric scattering matrix (PSM) of the first calibrator are required to be specified. The copolarized scattering properties, including the range information of the other two calibrators and the rotation angle of the third calibrator, can be acquired in the calibration process and used to verify the calibration accuracy     

Kinetics of picosecond pulse generation in semiconductor lasers with bimolecular recombination at high current injection

The kinetics of generating ultrashort light pulses by gain switching unbiased semiconductor lasers emitting relaxation oscillations is theoretically modeled and described using phase portraits. Biomolecular recombination processes and realistic injection current pulse shapes are incorporated in the model. Approximate analytical solutions of the rate equations are derived for high current injection. Laser pulse widths, pulse peak power, electrical to optical pulse delay times, and time difference to subsequent relaxation oscillations are computed. Their dependence on injection current to threshold current density ratio (J/J_{t}) and on material and laser design parameters is explicitly derived and is in good agreement with experiment. In particular the remarkable observation that the laser pulse width is broadly independent of the injection current rise and fall time can thus be understood.