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ARFTG Conference Digest-Fall, 56th

Date Nov. 2000

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Displaying Results 1 - 25 of 35
  • Carrier-to-Interference Ratio Estimation of Arbitrary Signals Distorted by Nonlinear Devices

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (171 KB)  

    This paper presents a new method for estimating the total carrier-to-interference ratio (CIR) of an arbitrary signal distorted by a nonlinear device. Using a kernel function derived from swept power two-tone intermodulation distortion (IMD) measurements, the CIR versus input power of a nonlinear device may be determined for any arbitrary input signal. Only a knowledge of the input signal peak-to-average power ratio (PAPR) distribution is required. Simulation results are compared to measured results of output signal CIR of a nonlinear amplifier fed by a CDMA signal over a range of power levels. Better than 1 dB agreement was achieved over a 14 dB range of input power. View full abstract»

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  • Behavioral models of microwave circuits with fading memory

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (175 KB)  

    We discuss how to build nonlinear input-output models of low-dimensional deterministic systems for both static and dynamic (feedback) systems with fading memory." Radial basis functions are used to build the models. The utility of these models is illustrated by building accurate and stable models for electronic circuits with dynamic (memory) effects. View full abstract»

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  • Network Analysis Beyond S-parameters: Characterizing and Modeling Component Behaviour under Modulated Large-Signal Operating Conditions

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (113 KB)  

    It is shown in this paper how the classical concept of the ¿network analyser¿ can be extended towards modulated and large-signal operating conditions. The concept is demonstrated by measuring the saturated behaviour of a MMIC amplifier, excited by modulated signals with CDMA characteristics. It is then illustrated how the measured data can be used to construct an accurate behavioural model. View full abstract»

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  • A New Technique for Low-Jitter Measurements Using Equivalent-Time Sampling Oscilloscopes

    Page(s): 1 - 3
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (32 KB)  

    A new timebase technology for equivalent-time sampling oscilloscopes is presented. The technology is based on the qualification of a high-Q resonator with traditional analog signal processing, and provides a startable oscillator for generating trigger-to-strobe delays with excellent long term jitter performance. View full abstract»

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  • Improving the Uncertainty Analysis of NIST's Pulse Parameter Measurement Service

    Page(s): 1 - 9
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (116 KB)  

    A new uncertainty analysis is being performed for NIST¿s pulse parameter measurement service that represents the new pulse parameter measurement and extraction process. This new analysis is expected to have lower uncertainties compared to those presently reported. View full abstract»

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  • A Quasi-Coherent Sampling Method for Wideband Data Acquisition

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (168 KB)  

    This paper proposes a quasi-coherent equivalent-time sampling method to acquire repetitive wideband waveform signals with high throughput. We have already proposed a new sampling system which incorporates the pretrigger ability and the time jitter reduction function for a fluctuated input signal while maintaining the waveform recording efficiency. The quasi-coherent sampling method proposed in this paper can be adopted to it in order to improve its data acquisition throughput significantly. Numerical simulation results show effectiveness of our proposed method. View full abstract»

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  • High-Frequency Behavior of Coupled CMOS Interconnects Built in Different Metallization Layers

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (87 KB)  

    In this paper we apply a broadband measurement method to determine the propagation characteristics of coupled-line structures fabricated in different metallization layers of a 0.25 ¿m CMOS technology. We show that the matrices of frequency-dependent line parameters, as extracted from calibrated four-port S-parameter measurements, agree well with data predicted by numerical calculations, and discuss the impact of metal level height above the substrate on the transmission characteristics. View full abstract»

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  • Experimental Results for Parasitic Coupling and Attenuation of Coplanar Waveguides on High Resistivity Silicon

    Page(s): 1 - 11
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (303 KB)  

    In high density MMIC circuits, parasitic coupling becomes a critical design consideration and adequate spacing between closely placed circuits is necessary to avoid unwanted interaction. In this paper, a measurement-based estimate for minimum spacing required between CPW lines fabricated on silicon is presented. It is shown that parasitic coupling between CPW lines can be reduced by a factor of 10dB if the silicon substrate around the ground plane is etched. Measured results for attenuation are also presented for CPW lines fabricated on a 425¿m thick Si substrate using 1¿m layers of either high temperature oxide (HTO) or evaporated SiO. It is shown that the loss on SiO is 3× lower when compared to SiO2 - based configurations. View full abstract»

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  • Accurate Probing of RF Amplifiers Using Vertical Interconnect Boards

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (60 KB)  

    Printed circuit boards with plug-in pins and edge-connectors for insertion into appropriate sockets on a mother-board are used in the electronics industry as functional circuit blocks. For example, functions such as additional RAM can be added to a personal computer by inserting cards with edge connectors to mate with the CPU mother-board. In RF amplifiers used in high-speed data transmission, video communication and broadband cable television, plug-in circuit boards save considerable real estate on the mother-board and facilitate plug-and-play convenience. At RF and microwave frequencies, it is very important to characterize the pin-socket interface on the mother-board so that the influence of its mismatch and other parasitic effects can be incorporated in the circuit design. In this paper, we discuss a calibration technique to compensate for such mismatch, and present measured data on a high-gain amplifier. View full abstract»

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  • Millimeter Wave Vector Analysis Calibration and Measurement Problems Caused by Common Waveguide Irregularities

    Page(s): 1 - 9
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (171 KB)  

    This paper was prompted by an effort to develop vector network analysis calibration kits for the WR-08 through WR-03 waveguide bands. A lack of repeatability (instability) of vector network analyzer (VNA) calibrations above 90 GHz was encountered which led to the investigation of not only the calibration kit artifacts but into the ¿MIL SPECS MIL.-F-3922/67B-xxx¿ defined tolerances and actual properties of commonly available components for these waveguide bands. The following frequent sources of errors were identified: 1) The common tendency of waveguide at these frequencies to be oversize causing the incorrect entry of the waveguide¿s cutoff frequency during VNA calibration. 2) Significant waveguide flange misalignment possible with current MIL SPECS specified tolerances with no widely accepted technique for precise alignment. 3) Common waveguide component irregularities that occur due to inadequately developed manufacturing and assembly processes and that are so small that they can only be discovered with microscopic examination. View full abstract»

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  • Evaluating and expressing uncertainty in complex S-parameter measurements

    Page(s): 1 - 13
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (149 KB)  

    This paper presents methods for evaluating and expressing the uncertainty associated with complex S-parameter measurements. The methods are based on internationally recommended guidelines [1] with extensions to accommodate the complex nature of the measurands. The treatment of measurements of both one-port and multi-port devices is presented. View full abstract»

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  • Modeling Load Variations with Artificial Neural Networks to Improve On-Wafer OSLT Calibrations

    Page(s): 1 - 13
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (182 KB)  

    We demonstrate that on-wafer open-short-load-thru (OSLT) calibrations of vector network analyzers can be improved by applying artificial neural networks (ANNs) to model the correlation between DC resistance and RF variations in load terminations. The ANNs are trained with measurement data obtained from a benchmark multiline thru-reflect-line (TRL) calibration. The open, short, and thru standards do not vary significantly from wafer to wafer, so we also model these standards using ANNs trained with calibrated measurement data chosen from an arbitrary wafer. We assess the accuracy of five OSLT calibrations with varying load terminations using the ANN-modeled standards, and find that they compare favorably (a difference of less than 0.04 in magnitude at most frequencies) to the benchmark multiline TRL calibration over a 66 GHz bandwidth. We demonstrate that ANN models offer a number of advantages over using calibrated measurement files or equivalent circuit models, including ease of use, reduced calibration times, and compactness. View full abstract»

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  • Lumped-Element Models for On-Wafer Calibration

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (62 KB)  

    We examine electrical models for lumped-element impedance standards used in on-wafer network-analyzer calibrations. We illustrate the advantages of using models that are complicated enough to replicate the actual electrical behavior of the lumped standards, but do not have more degrees of freedom than absolutely necessary. View full abstract»

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  • Load Models for CPW and Microstrip SOLT Standards on GaAs

    Page(s): 1 - 11
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (427 KB)  

    We present an analysis of the types of models typically available within modern network analyzers for Short-Open-Load-Through (SOLT) calibrations. We find that the models for the reflect standards effectively handle their task. We also show that in some cases for well-behaved loads the analyzer models adequately handle the job, while in other cases fall short. This analysis was carried out for both microstrip and coplanar waveguide transmission line structures realized on GaAs substrates. We also explore how more complicated load models might be used to provide improved fits to measured data of on-wafer loads. View full abstract»

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  • Nonlinear Characterization of Multiple Carrier Power Amplifiers

    Page(s): 1 - 8
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    In this paper the input signal dependence on the nonlinear transfer function of power amplifiers is discussed. It is shown by measurements that the nonlinear behavior of the amplifier does indeed depend on the input signal. This is seen to be true both for AM/AM and AM/PM distortion. The implication is that a traditionally VNA swept CW cannot be used to obtain the AM/AM and AM/PM distortion that will actually take place in the amplifier during real life conditions, and that test signals which closely resembles the signals that will actually be used are necessary. The focus is to present a new possible measurement methodology necessary to target the demands of accurate characterization raised by multiple carrier power amplifiers MCPA:s. We briefly discuss the mechanisms that lies behind this behavior. The test signal selection and creation is discussed, as well as a method of producing highly linear ¿80 dBc WCDMA signals for ACP testing. Finally we present practical measurement results on AM/AM and AM/PM distortion obtained with swept, pulsed and multi-tone input signals to prove the input signal dependence. Practical results is given for high power narrowband Class AB LDMOS amplifiers intended for the 2.11-2.17GHz WCDMA band and for medium power Class A GaAs FET amplifiers. View full abstract»

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  • The Microwave Component Analyzer: A Novel Instrument for Measuring Pulsed or CW Signal-to-Noise Ratio

    Page(s): 9 - 12
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (137 KB)  

    The Microwave Component Analyzer (MCA) is introduced as a novel instrument for making automated signal-to-noise ratio (SNR) measurements in pulsed or CW mode. With an advanced vector demodulator, the MCA converts a microwave signal into error-corrected I (In-phase) and Q (Quadrature-phase) digitized signals. Utilizing a rotating phase reference technique, vector demodulator linear distortions are automatically error-corrected with an internal self-calibration. High-speed digital signal processing of the I and Q signals results in the ability to make real-time measurements of SNR. The noise behavior of a pulsed amplifier in compression is measured by the MCA and the results are compared to theory. View full abstract»

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  • A Wideband Method for the Rigorous Low-Impedance Loadpull Measurement of High-Power Transistors Suitable for Large-Signal Model Validation

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2070 KB)  

    This paper presents a rigorous method for low impedance loadpull measurements using a 6-section Tschebyscheff transforming water-cooled pre-matching test fixture. The transformers were designed to be able to accurately determine S-parameters that represent each fixture half at the fundamental frequency of operation fo and its second and third harmonics, 2fo and 3fo. A two-tier non-50 ¿ TRL calibration technique was used to establish the measurement reference planes. In order to accurately establish the calibrated system impedance, a simulated Time Domain Reflectometry (TDR) technique was employed. The calibration of the loadpull system was confirmed by calculating the difference between the measured and calculated transducer gain (¿Gt). This difference provides a measure of the measurement uncertainty. The largest uncertainty, in areas of interest on the Smith chart, was found to be 0.25 dB. The fixture was successfully utilized to measure the loadpull performance of one of Motorola's LDMOS, 90 Watt, 1.9 GHz high power transistors. View full abstract»

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  • Synchronous Sampling and Applications to Analytic Signal Estimation

    Page(s): 1 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3579 KB)  

    Analysis of signals in Hilbert space is used for narrowband communications signals in both linear and exponential modulation formats (i.e. QAM, QPSK, FSK etc). Less well known perhaps is the use of the analytic signal in broadband, non-linear modulation analysis. Inter-symbol interference (ISI), Deterministic Jitter, phase noise, and AM-PM conversion are examples of non-linear system impairments whose measurement and analysis are simplified using analytic signal techniques in Hilbert space. Synchronous sampling allows for direct demodulation and extraction of baseband In-phase and Quadrature channels. Its application to measurement of both random and deterministic jitter, phase noise, and AM-PM effects is discussed, as well as calibration methods and other accuracy enhancement techniques. Synchronous sampling is contrasted to conventional waveform recorder timebases: real-time sampling, random equivalent-time sampling, and triggered sweep. Synchronous Sampling uses a phase locked timebase with delay control and carrier extraction to provide a rotating reference frame in Hilbert space, from which the signals are analyzed in three dimensions: I and Q vs. Time or Modulation Frequency. View full abstract»

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  • Microwave Electric-Field Mapping Using Optical-Fiber-Mounted Electro-Optic Probes

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (255 KB)  

    A microwave electric-field mapping system based on electro-optic sampling has been developed using micromachined gallium arsenide crystals mounted on gradient-index lenses and single-mode optical fibers. Three orthogonal polarization components of the electric field are distinguished, and two-dimensional field images are obtained by scanning the fiber-based probes in a plane above the device under test. Because the probes are simple dielectrics and require no metal or electrodes to extract the electric field amplitude and phase, they are uniquely useful in the imaging of the aperture-plane region of antennas and arrays, where they provide complete information on radiated, guided, and evanescent waves. Due to the high level of versatility afforded by the optical-fiber coupling, this diagnostic testing can be extended not only to open, guided-wave structures, but also to shielded microwave circuits and packages. View full abstract»

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  • Picosecond pulse propagation images and oppositely polarized pulse shapes on CPS lines measured by a Scanning Force Optoelectronic Microscope

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (264 KB)  

    We have developed a novel ultra-fast voltage measurement system, the scanning force optoelectronic microscope (SFOEM), by integrating a scanning force microscope (SFM) and an optical sampling technique. This paper describes a method by which a 2ps pulse propagation image directed along the edge of a coplanar strip (CPS) has been recorded using the SFOEM. It also describes how oppositely polarized pulses on each line of the CPS were measured by the SFOEM. These results demonstrate that the SFOEM is a useful tool not only for measuring ultra-fast voltage and pulse propagation images but also for analyzing the operation of ultra-fast LSI devices. View full abstract»

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  • Electro-optic sampling of coplanar to coaxial transitions to enhance the calibration of fast oscilloscopes

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (48 KB)  

    Improvements to the NPL time domain measurement facility for the calibration of fast oscilloscope risetime are described. Particular emphasis is placed on characterising a coplanar waveguide to coaxial connector transition between a photoconductive pulse generator and the input of an oscilloscope sampling head. Two methods of measuring the transition are described and it is shown that test electrical pulses of less than 4 ps width can be applied to the oscilloscope. View full abstract»

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  • Overview of applications of optical measurements in microwave circuit and antenna array design

    Page(s): 1 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (649 KB)  

    An overview of both photoconductive sampling and optoelectronic mapping measurements (developed at the University of Michigan by the Whitaker and Katehi group) and their benefit in expediting microwave circuit and array design is presented. In particular, photoconductively sampled time-domain waveforms of switched-mode nonlinear power amplifiers and X-band and high-efficiency multipliers at C-band will be discussed. The high-impedance optical sampling probe enables measurements of waveforms within a microwave circuit. This in turn enables us to validate designs of nontraditional nonlinear circuits, as well as to diagnose problems associated with improperly terminated harmonics, leading to new improved circuit designs. We also present near-field measurements using an electro-optic crystal probe. As an example, a 30 GHz (Ka-band) active amplifier antenna array power combiner is examined in detail. The effects of mutual coupling between array elements, and bias line influence on RF mutual coupling between elements are presented. An extensive list of references that contain more details of the overviewed material is also given. View full abstract»

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  • Identification and Measurement of Transmitter Non-Linearities

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (57 KB)  

    In this article the effects of non-linearities and other impairments in a direct up-conversion transmitter is investigated. By using simple non-linear models for the non-linearities at baseband and for the power amplifier, a total mathematical model of the transmitter is obtained. From the model it can be seen that both the amplitude and the phase distortion of the transmitter are dependent on both the phase and the envelope of the input signal. The parameters of the non-linear baseband and RF distortion of this model are then identified separately by studying the amplitude and phase distortion of the output signal. The method is verified by measurements and it is found that the identified parameters can be used to accurately re-generate the measured output signal in the sense that all main distortion products, i.e. larger than ¿60 dBc, of the re-generated signal will be within a dB of the distortion products of the measured signal. View full abstract»

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  • Improved Uncertainty for the Noise Source based on the Adapter Removal Methods

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (24 KB)  

    Noise is the fundamental to our understanding communication. For the last ten years and with the emerging of the wireless communication industry, the demand of making high accurate noise generator measurements has increased dramatically. The increased accuracy specification of the Noise Figure Analyzers is based in part on better calibrations of the Noise Source. Our primary noise source standards were calibrated by NIST in APC-7, X-band, P-band, K-band, R-band, and Q-band. Calibrated adapters are used on the NIST calibrated noise sources to characterize the system for the connector option of the noise source being used. The uncertainty of these adapter calibrations degrades the reported uncertainty. The old method would measure pairs of adapters (P-band to Type-N male & Type-N female to P-band) and split the loss of the pair as a best guess of each adapter loss. An increase in the uncertainty budget was made. The new method will require the testing of 3 different adapters. Each adapter is paired back-to-back with the two others and a measurement is made. This results in 3 measurements, 3 equations, and 3 unknowns, which can be solved for each adapter¿s transmission loss. No assumption about loss split is make. View full abstract»

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  • Finite Aperture Time and Sampling Jitter Effects in Wideband Data Acquisition Systems

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (270 KB)  

    This paper presents explicit analysis of the output error power in wideband sampling systems in the presence of finite aperture time and sampling jitter. Finite aperture time and sampling jitter are crucial for wideband sampling systems to capture high-frequency signals in high precision. Finite aperture time (or finite aperture window) works as a low pass filter and hence it degrades the high-frequency performance of sampling systems while aperture jitter misleads data acquisition timing points, which causes large errors for high-frequency (and hence large slew rate) signal acquisition. In this paper, we discuss their effects explicitly in case that not only finite aperture time and sampling jitter exist individually but also they exist together for almost any aperture window function with jitter of Gaussian distribution. These results are theoretically fundamental, and are useful for designing wideband sampling data acquisition systems. Experimental measurements are being performed to verify our theoretical results and these may be also reported at the conference. View full abstract»

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