Calibration of sampling oscilloscopes with high-speed photodiodes

We calibrate the magnitude and phase response of equivalent-time sampling oscilloscopes to 110 GHz. We use a photodiode that has been calibrated with our electrooptic sampling system as a reference input pulse source to the sampling oscilloscope. We account for the impedance of the oscilloscope and the reference photodiode and correct for electrical reflections and distortions due to impedance mismatch. We also correct for time-base imperfections such as drift, time-base distortion, and jitter. We have performed a rigorous uncertainty analysis, which includes a Monte Carlo simulation of time-domain error sources combined with error sources from the deconvolution of the photodiode pulse, from the mismatch correction, and from the jitter correction.     

基于光脉冲源的标准脉冲法的宽带取样示波器校准技术研究

本文构建了基于光脉冲源的示波器校准系统,用标准脉冲法实现了对宽带取样示波器Agilent 86100C的70GHz取样模块86118A的校准.在校准实现过程中,首次综合研究了三种时基误差对校准结果的影响,并采用互相关算法去除时基漂移,最小二乘法修正时基失真,利用反卷积去除时基抖动.实验结果表明,本文方法实现了对70GHz宽带取样示波器的校准,有效地去除了时基误差,满足校准精度的要求.     

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     

宽带取样示波器Nose-to-Nose校正理论的新进展

本文根据电路、信号与系统理论并结合实际校测工作对一种适于高速/宽带取样示波器性能校正的新方法——Nose-to-Nose (NTN)法的理论基础作了研究,分析了该方法中的重要信号kick-out脉冲,推导了其数学表达式,提出了"kick-out脉冲与示波器取样系统的阶跃响应成比例"的新观点,最后讨论了NTN方法误差及电路非线性和非对称性对校正的影响.     

Systematic Error of the Nose-to-Nose Sampling-Oscilloscope Calibration

We use traceable swept-sine and electrooptic-sampling-system-based sampling-oscilloscope calibrations to measure the systematic error of the nose-to-nose calibration, and compare the results to simulations. Our results show that the errors in the nose-to-nose calibration are small at low frequencies, but significant at high frequencies.     

Automatic network measurements in the time domain

The time-domain automatic network analyser (TDANA) is described. It utilizes time-domain measurements and the fast Fourier transform to obtain frequency-domain scattering parameters. A TDANA consists of a pulse generator, sampling oscilloscope, and a minicomputer. The present state of the art for TDANA's includes frequency coverage from dc to 18 GHz in a single instrument and complex scattering parameter measurement uncertainties of the order of 1 percent.     

Calibration and error analysis of a picosecond pulse waveform measurement system at NBS

The primary system used at NBS, Boulder, CO, to measure fast (picosecond-nanosecond range), repetitive, electrical pulse parameters consists essentially of a wide-band (dc-18 GHz) sampling oscilloscope interfaced to a minicomputer. This paper describes the major calibration and analysis techniques used to reduce the effects of errors inherent in this system, both deterministic and random in nature.     

Uncertainty of ESD Pulse Metrics Due to Dynamic Properties of Oscilloscope

This paper investigates how dynamics of an HF oscilloscope affects standardized metrics (i.e., rise time and peak value) of a recorded electrostatic discharge (ESD) current pulse and evaluates the oscilloscope measurement uncertainty. A frequency-domain dynamic model of the oscilloscope, based on measurements of the input reflection and voltage gain magnitude, is derived. The complex voltage gain is approximated with a transfer function to take into account unmeasured phase shift. A high-order discrete-time filter is designed to fit the measured voltage gain magnitude not only in the passband, but also beyond it as well. Since the measured data are burdened with measurement uncertainties, the worst-case deviations of the oscilloscope input impedance and the voltage gain (in the form of envelopes of the frequency responses) are calculated, and components of Type B uncertainty of the ESD pulse metrics corresponding to these deviations are estimated using the sensitivity method.      

Open-ended metallized ceramic coaxial probe for high-temperaturedielectric properties measurements

A metallized ceramic coaxial probe has been developed for high temperature complex permittivity measurements. The probe is made of alumina and metallized with a 3.0-mil-thick layer of moly-manganese, and a 0.5-mil-thick protective coating of nickel plating. It is shown that based on carrying out the network analysis calibration procedure up to 1000°C, and on actual dielectric properties measurements, the probe provides accurate dielectric measurements over a broad frequency range (500 MHz to 3 GHz) and for temperatures up to 1000°C. An uncertainty analysis based on two different calibration techniques was also given to help quantify possible measurement errors     

Measurement of magnitude and phase of harmonics generated innonlinear microwave two-ports

A method for simultaneously measuring the magnitude and phase of the harmonics generated by a microwave two-port is reported. The two-port under test is driven with a sinusoidal microwave signal strong enough to force it into nonlinear operation. Its output harmonics are measured in the frequency domain with a setup that includes a vector network analyzer. For phase calibration at the harmonic frequencies, a millimeter-wave Schottky diode is used as a reference device. The system allows the measurement of harmonics with a phase accuracy of about ±10° at 20 GHz (referred to f₁=5 GHz). It can be built for any frequency (<40 GHz) at which a vector network analyzer and a suitable signal generator with multiplier are available. For low-amplitude harmonics, higher sensitivity compared to time-domain measurements with a sampling scope results in better measurement accuracy. The accuracy should improve further if the nonideality of the diode reference circuit is characterized more precisely     

Design of minimum-phase digital filters as the sum of two allpass functions using the cepstrum technique

A new and practical approach using the cepstrum technique is proposed in the design of minimum-phase digital filters as the sum of two allpass functions. The desired magnitude response is specified in the frequency domain. Its corresponding minimum-phase response is then obtained from the desired magnitude response. The desired phases for the two allpass filters are obtained from the magnitude and phase responses. For both filters to be stable, the corresponding denominator polynomials are minimum phase. The filter coefficients are obtained from the desired phases using the cepstrum technique. Design examples show that the method works well for both classical filter specification and general magnitude specification in the frequency domain.     

Characterization of the complex permittivity of brain tissues up to 50 GHz utilizing a two-port microstrip test fixture

Broad-band complex-permittivity values of biological tissues above 20 GHz obtained from direct measurements have not been reported in the literature. This paper presents for the first time the measurement results of complex permittivity of brain grey and white matters from 15 to 50 GHz utilizing a two-port microstrip test fixture. Test fixture S-parameters are simulated employing the finite-element method. To apply the data obtained from the simulation in complex-permittivity extraction, an efficient procedure, using the linear least square technique, is introduced to fit the modeling results to a rational function of complex permittivity, which is similar to the transfer function for a linear system. This fitting procedure is computationally more efficient than the previously developed fitting methods. Measurements are performed on slices of brain sample using a calibrated network analyzer utilizing custom designed through-reflect-line (TRL) calibration standards. The measurements are corrected for the residual errors observed in the measurement results due to the lack of performance repeatability of coaxial-to-microstrip launchers utilized in the TRL calibration standards. Finally, the measured results for brain matters are fitted to a single term Cole-Cole relation representing the dispersion characteristics of white and grey matters up to 50 GHz.     

An improved sliding-load calibration procedure using asemiparametric circle-fitting procedure

Circle-fitting problems often occur in microwave engineering when dealing with variable delays, e.g., during calibration using a sliding load. This paper proposes an efficient semiparametric circle-fitting procedure, which takes into account the phase relationships over the frequencies. It produces more accurate results than the standard sliding-load calibration, requires only three positions on the sliding load for the whole frequency band, and is more robust to the settings of the positions of the sliding load. The proposed method also has the ability to detect whether or not the sliding load is defective or out of its specifications. This can be done by using only three positions on the sliding load. Optimal-position settings are then proposed. The performance of the proposed method is illustrated on sliding-load measurements up to 50 GHz, demonstrating the ability of detecting modeling errors and showing that the accuracy of the proposed method using three positions is comparable to the standard method with six positions     

Measuring the frequency response of gigabit chip photodiodes

We describe a calibration and measurement procedure for determining the intrinsic frequency response of gigabit chip photodiodes embedded in simple test fixtures. The procedure is unique because we make the measurements in the time domain using a calibrated oscilloscope, and we then apply frequency-domain mismatch corrections to remove the effects of the fixture, bias T, and cables from the measurements. We demonstrate the procedure on photodiodes with an active region of approximately 150-μm diameter excited by short 800-nm wavelength optical pulses     

New method for determining the permeability tensor of magnetizedferrites in a wide frequency range

To provide a broadband method for measuring the complex permeability tensor components of magnetized ferrites we have realized a nonreciprocal rectangular waveguide cell. A network analyzer setup is used to measure the scattering parameters of the cell over a wide range of frequencies. The nonreciprocity of the cell permits the determination of the permeability tensor components in a single experimental phase. Complex permittivity and complex components of the permeability tensor are computed from a data-processing program, taking into account higher order modes excited at the cell discontinuities and using a numerical optimization procedure to match calculated and measured values of the S-parameters. We have studied the convergence of the calculated S-parameters as the number of modes taken into account in the calculations. Sensitivity to the input parameters for the optimization algorithm is discussed. A thru-reflect-line calibration in conjunction with a specific sample holder is used to eliminate systematic errors inherent in the S-parameter measurements. Measured complex permeability tensor components data for microwave ferrites are presented at X-band frequencies (8-12 GHz). Experimental results are in good agreement with theoretical results given by the ferromagnetic material theory     

基于Nose-to-Nose校准法的取样示波器 冲激响应的一种算法

本文根据时变电路概念和信号与电路系统理论,利用Nose-to-Nose(NTN)校正法,对取样示波器的双二极管平衡型取样电路建立了时变线性电路模型,导出了kick-out脉冲和取样系统冲激响应的时域表达式,证明了该脉冲是NTN校正中的零输入响应而非冲激响应,提出了从kick-out脉冲中提取时间常数从而确定取样器冲激响应的新的数据处理方法与公式,有效地解决了NTN校正中取样管结电容变化对校正精度的影响问题.     

应用反卷积实现脉冲计量中的信号重构与系统辨识

本文研究了在脉冲计量领域中的基于反卷积算法的信号重构与系统辨识。我国目前的脉冲参数国家基准过渡时间为725±050ps,带宽为563±58%GHz。如果采用传统的计量方法,该基准无法实现对标称带宽为70GHz的Agilent86100C高速取样示波器以及标称过渡时间为5ps的Picosecond4016负阶跃脉冲源进行校准。本文将反卷积算法引入到测量数据处理中,并结合具体问题对传统的反卷积算法进行了改进,克服了传统的反卷积算法对阶跃信号计算误差过大的问题,并进行了实验验证,实现了量值传递。      

Design and Measurement of a Digital Phase Locked BWO for Accurately Extracting the Quality Factors in a Biconcave Resonator System

A long loop phase locked backward-wave oscillator (BWO) for a high quality factor resonator system operating at D-band frequencies (130–170GHz) was described, the phase noise of the phased locked BWO was analyzed and measured at typical frequencies. When it used with a high quality factor open resonator for measuring the quality factor of simple harmonic resonators based on the magnitude transfer characteristic, this system has proven to be capable of accurate measuring the quality factor as high as 0.8 million with an uncertainty of less than 1.3% (Lorentzian fitting) at typical frequencies in the range of 130GHz–170GHz.     

基于单片机和FPGA的数字示波器的设计

随着电子技术的发展,对电路测量的要求越来越高。提出了一种基于数字示波器原理,以单片机和FPGA为控制核心的数字示波器实现方法。系统由信号调理、程控放大、比较整形和时钟产生、采样控制、测频模块和校准信号产生等模块组成。可测频率范围10Hz到10MHz,幅度范围2mV到20V,垂直灵敏度共11档,扫描速度共21档。实时采样...     

Nose-to-nose校准技术的理论分析

Nose-to-nose校准技术的理论基础是:kick-out脉冲正比于取样示波器系统的冲激响应.Jan verspecht博士和美国国家标准技术研究院(NIST)用S参数法对此进行了详尽的分析.本文从电路理论分析入手,对kick-out脉冲产生的机理重新进行了分析,得出了十分有用的数学表达式和结论:kick-out 脉冲不仅与电路参数有关,而且与选通脉冲有关.这一结论并被计算机的仿真所证实,这用以前的理论是无法解释的.可以说本文结论进一步完善了NTN校准技术的理论依据.