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Microwave Measurements Conference (ARFTG), 2010 75th ARFTG

Date 28-28 May 2010

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Displaying Results 1 - 25 of 30
  • [Front cover]

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    Freely Available from IEEE
  • [Front matter]

    Page(s): 1 - 2
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    Freely Available from IEEE
  • Modulated signals for wireless communications

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    Freely Available from IEEE
  • Modern cellular wireless signals

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (905 KB) |  | HTML iconHTML  

    With the evolution of cellular wireless systems and services, the on-air signals themselves are also undergoing very significant transformations. This paper provides a survey of the active and coming-soon signal types adopted for cellular wireless systems around the world. Focus is on modulation schemes, along with various measures used to characterize the signals before and after power amplification. Cost-benefit tradeoff information is introduced to provide perspective on this signal evolution. View full abstract»

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  • Measurement and correction of residual nonlinearities in a digitally predistorted power amplifier

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (622 KB) |  | HTML iconHTML  

    A reduced cost method for the measurement and correction of residual nonlinearities in a digitally predistorted transmitter is proposed. The original system uses a calibration signal applied off-line and a cancellation loop with a square law detector to measure residual nonlinearities. The approach is improved by replacing the calibration signal with the actual signal transmitted, resulting in an on-line measurement system. A further extension integrates several measurements over the input envelope range to adapt a fourth-order polynomial predistorter. Simulation results for a WCDMA input with a 101 carrier configuration show that the proposed approach for measuring residual nonlinearities and estimating predistortion coefficients is effective. View full abstract»

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  • Experimental sensitivity analysis of multi-standard power amplifiers nonlinear characterization under modulated signals

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1723 KB) |  | HTML iconHTML  

    This paper proposes an experimental analysis focusing on the sensitivity of three behavioral models, Memory Polynomial (MP), Augmented Hammerstein (AH) and the two hidden layers artificial neural networks (2HLANN) to the characteristics of the input signal driving the power amplifier (PA) to be linearized. The analysis is carried out by changing separately each signal characteristic, respectively the peak to average power ratio (PAPR), the Probability density function (PDF), and the modulation bandwidth and assess the sensitivity of the DPD to that change. When used to linearise a 250 Watt peak-envelop-power Doherty PA, the considered models showed relatively small sensitivity to the variation of these signal characteristics. Yet, the 2HLANN was found to be the most robust model with excellent linearization capabilities. View full abstract»

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  • A simplified extension of X-parameters to describe memory effects for wideband modulated signals

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (875 KB) |  | HTML iconHTML  

    An original way is presented to model memory effects of microwave amplifiers in the case of wideband modulated signals. The model is derived as a limiting case of the more general dynamic X-parameter theory. For a given component, the model is identified from pulsed envelope X-parameter measurements performed with an NVNA. The resulting nonlinear X-parameter model is quantitatively described by a 2-variate kernel function that enables the derivation of an optimal static AM-AM AM-PM characteristic for every possible input envelope probability density function. The model is validated by performing a set of 2-tone experiments. The model can be implemented in the ADS circuit envelope simulator. View full abstract»

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  • Multi-harmonic broadband measurements using an large signal network analyzer

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1227 KB) |  | HTML iconHTML  

    A new testbed was developed with an LSNA to perform multi-harmonic broadband measurements for periodically modulated signals with bandwidth exceeding the IF receiver bandwidth of the LSNA. This testbed is intended for characterizing PAs using periodically modulated (multitone) signals often referred as multisines. Multisine signals can be synthesized to approximate the CCDF and PAPR of digitally modulated signals such as WiMAX and LTE (Long Term Evolution). In the experiment conducted a multisine with 13 tones distributed over 15 MHz was used which provided a PAPR of 6 dB. Using this excitation, the nonlinear response of a 80 W Doherty GaN PA at 2.16 GHz was characterized over a 80 MHz bandwidth. Inband signal distortion and spectral regrowth were recorded in the 63 tones measurement over the 80 MHz measurement bandwidth targeted at both the fundamental and second harmonic. This increased measurement bandwidth enables one to characterize the nonlinear vector response of the PA in its 3rd and 5th order inter-modulation bands at the fundamental frequency. The broadband vector results at the second harmonic obtained in the same measurements provides additional invaluable information for the multi-harmonic optimization of the efficiency of the Doherty PA under test. It is believed that the multi-harmonic broadband vector characterization capabilities provided by the reported testbed should assist with the development and verification of multi-harmonic behavioral models for wideband modulated signals. View full abstract»

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  • A VNA based broadband load-pull for non-parametric 2-port Best Linear Approximation modeling

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (551 KB) |  | HTML iconHTML  

    In this paper the Best Linear Approximation (BLA) of a full 2-port nonlinear dynamic system is extracted under broadband load-pull conditions. Starting from a series of VNA Measurements and broadband multisine excitations at both ports, the frequency response function, the covariance matrix of the output noise, and the covariance matrix of the output nonlinear distortions are estimated as a function of the frequency. Using well designed periodic excitations signals, these results are obtained with limited user interaction, making the method accessible for practitioner engineers. View full abstract»

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  • An intelligence driven active loadpull system

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (760 KB) |  | HTML iconHTML  

    This paper describes how the application of the PHD model can add intelligence to an open loop active loadpull system. This intelligence driven approach by providing for an improved prediction of the operating conditions required to emulate a specified load speeds up the load emulation convergence process by minimizing the number of iterations to predict the injected signal, therefore making more efficient use of a measurement system. The results were validated by carrying out loadpull measurements on the fundamental tone of a 10 × 75um GaAs HEMT, operating at 3 GHz. View full abstract»

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  • Investigation of X-parameters measurements on a 100 W Doherty power amplifier

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1402 KB) |  | HTML iconHTML  

    In this article we describe a high-power reflectometer set-up specifically designed for large-signal nVNA measurements for the extraction of X-parameters. The heart of the measurement set-up is an Agilent N5242A PNA-X in nVNA mode. We have measured a Doherty amplifier constructed from a 2-stage, dual-path RF power amplifier IC. This power amplifier can deliver in excess of 100 W in Doherty mode, and these measurements represent the highest power X-parameter extraction reported to date. View full abstract»

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  • A multi-step phase calibration procedure for closely spaced multi-tone signals

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1140 KB) |  | HTML iconHTML  

    In this work we present a novel phase calibration procedure suitable for the waveform reconstruction of closely spaced multi-tone signals. The proposed multi-step calibration approach is based on the phase alignment of the calibration error terms measured with different frequency grids generated by the harmonic phase reference. The method achieves a reduction in the needed multiplication order of the phase reference to cover the intended measurement frequency range. The calibration procedure is implemented on an Agilent PNA-X platform, which uses external hardware extensions, e.g. low frequency bridges, for the accurate measurement of the baseband frequency components. View full abstract»

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  • Traceable calibration of Vector Signal Analyzers

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (713 KB) |  | HTML iconHTML  

    We have developed a calibration technique for Vector Signal Analyzers (VSA) that provides traceability to primary standards. This technique has been implemented using standard commercial equipment. A multisine signal generator provides detailed magnitude and phase stimulus over the instrument bandwidth and a Digital Sampling Oscilloscope (DSO) measures the same multisine waveform. Traceability is provided via the DSO, calibrated against the primary standard (Electro-Optic Sampler). The VSA can be characterized over its full-bandwidth (magnitude and phase) at any operating frequency. The reproducibility of three different multi-sine measurements, averaged over an 80 MHz bandwidth was 3.4% (power) and 1.3 degrees (phase). View full abstract»

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  • A novel method for measuring phase and group delay of mixers without a reference mixer

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2181 KB) |  | HTML iconHTML  

    Making phase and group delay response measurements on mixers and frequency converters has traditionally been a difficult and complicated process, requiring either modulated-signals (and demodulation), two-tone signals (a special form of modulation) or a system with a reference or re-converting mixer. This paper presents a method to measure the phase response of a mixer on a VNA using a novel phase-measurement method which can measure the input and output phase response independently, computing the transfer response directly. This method relies on a VNA system which utilizes swept-frequency phase-coherent sources and receivers to maintain a common phase reference. A software phase-locking method allows it to operate on frequency converters which have an in-accessible embedded LO, along with a well established method of calibration. View full abstract»

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  • A new 75–110 GHz primary power standard with reduced thermal mass

    Page(s): 1 - 4
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1139 KB) |  | HTML iconHTML  

    Primary power standards are required to provide traceability for measurements. NPL has recently built a new primary power standard for use in the 75 GHz to 110 GHz band. Compared to NPL's older standard (which has been used for several decades) the new system has a reduced thermal mass and improved thermal isolation. This gives slightly reduced overall uncertainties and an improvement in usability. Improvements in manufacturing technique offer the promise of using a similar design in the 110 GHz to 170 GHz band and work on a calorimeter for this band has begun. View full abstract»

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  • Some effects of error term interpolation on network analyzer uncertainties

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (968 KB) |  | HTML iconHTML  

    Practically, many network analyzer measurements (both large signal and small signal) are performed at frequencies other than those where the calibration was performed in order to save time and effort. Typically, the error terms are simply interpolated in some way to calibrate at the new frequencies. Under what circumstances and how this interpolation is done can significantly affect the uncertainties of the measurement. This paper explores the characteristics of this interpolative error and how its impact can sometimes be assessed. Of particular note is that the hardware dependence of this effect is considerably larger than for many other components of uncertainty. View full abstract»

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  • Impact of the pulse-amplifier slew-rate on the pulsed-IV measurement of GaN HEMTs

    Page(s): 1 - 7
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1701 KB) |  | HTML iconHTML  

    The influence of the non-ideal response of the pulse-amplifier on the trap and self-heating dynamics, and hence, on the drain-current transient in a GaN HEMT is studied with new trap and self-heating models. It is shown that the study of the trap and self-heating dynamics requires a proper correction technique that accounts for the change in trap-potential, trap time-constant and thermal response due to the non-ideal response of the pulse-amplifier. Several post-measurement data correction techniques are discussed and shown to be incapable of predicting the true drain-current transient. A pre-measurement terminal correction technique using a new version of the pulse measurement system is used to solve the problem. View full abstract»

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  • A novel method for direct impedance measurement in microwave and mm-wave bands

    Page(s): 1 - 5
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (899 KB) |  | HTML iconHTML  

    A novel method for direct impedance measurement using a common vector network analyzer (VNA) is introduced. In commonly used methods impedance or admittance of a device under test (DUT) is derived from measured value of its reflection coefficient causing serious accuracy problems for very high or very low impedances. The proposed method makes possible to measure quantity directly proportional to the value of the impedance or admittance of the DUT. This enables us to accurately measure even impedances that are extremely different from value of the 50Ω reference impedance. The method can also significantly reduce effect of uncertainties of the VNA. A suitable calibration technique is suggested and fully mathematically described. The concept of the new method was verified by software simulation. View full abstract»

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  • Inter-laboratory comparison of reflection and transmission measurements in WR-06 waveguide (110 GHz to 170 GHz)

    Page(s): 1 - 10
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2204 KB) |  | HTML iconHTML  

    This paper describes an exercise that was undertaken recently to compare reflection and transmission measurements in rectangular metallic waveguide from 110 GHz to 170 GHz (i.e. in the WR-06 waveguide size). The comparison involved making measurements on four devices fitted with `precision' MIL-DTL-3922-67D style flanges. These devices were circulated amongst the nine organizations that chose to participate in the exercise. The comparison took place between August 2008 and September 2009. Results from the exercise are presented in graphical form along with a statistical summary showing average variability for the measurements. The authors believe this is the first time that such a comparison of measurements has been made at these frequencies. These results therefore provide a benchmark for the current state-of-the-art for measurements made in waveguide at these frequencies. View full abstract»

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  • Calibration standards for digital modulation error based on CW, AM or PM signal

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (3060 KB) |  | HTML iconHTML  

    Digital modulation signal is the main bearer of modern information transmission; modulation error parameters include Error Vector Magnitude (EVM), MagErr and PhaseErr. However, there are problems for metrology of digital modulation error: first, the signal source and vector signal analyzers calibrates each other, and forms a closed-loop, the calibration is not traceable. Second, digital modulation error are set in the “0” point in calibration. To solve the problems, we propose a new method: use combination of two CW, analog AM or PM signal, to construct an “equivalent MPSK signals” with certain modulation error. The equivalent MPSK signals' EvmRms, EvmPeak, MagErrRms, MagErrPeak, PhaseErrRms and PhaseErrPeak is are solely decided by power ratio of two CW, or by AM depth or PM phase deviation, and can be calculated accurately, and are continuously adjustable within a wide range. Experiment shows that the method is effective. This has established a standard signal with digital modulation error, it's could be used to calibrate vector demodulation functions of vector signal analyzer (VSA) and wireless communications tester. View full abstract»

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  • Harmonic load pull of high-power microwave devices using fundamental-only load pull tuners

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1427 KB) |  | HTML iconHTML  

    This paper presents a high-power high-efficiency PA design method using traditional fundamental-frequency load pull tuners. Harmonic impedance control at the virtual drain is accomplished through the use of tunable pre-matching circuits and full-wave FEM modeling of package parasitics. A 10-mm gate periphery GaN transistor from TriQuint is characterized using the method, and load-pull contours are presented illustrating the dramatic impact of varying 2nd harmonic termination. A 3rd harmonic termination is added to satisfy conditions for class-F-1 load pull, resulting in an 8% efficiency improvement over the best-case 2nd harmonic termination. The method is verified by design and measurement of a 36-W class-F-1 PA prototype at 2.14GHz with 81% drain efficiency and 14.5 dB gain (78% PAE) in pulsed operation. View full abstract»

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  • S-functions behavioral model order reduction based on narrowband modulated large-signal network analyzer measurements

    Page(s): 1 - 6
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (734 KB) |  | HTML iconHTML  

    In this paper we report for the first time on order reduction applied to S-functions behavioral models. The most dominant model parameters are selected based on the relative uncertainty of their estimated values evaluated against a threshold value. The selection procedure is performed on the same measurement data that is used to extract the model and obtained using a large-signal network analyzer. High level of model order reduction, achieved without any substantial loss of the prediction accuracy, is demonstrated on S-functions extracted for a packaged pHEMT device. View full abstract»

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  • X-parameter measurement challenges for unmatched device characterization

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (984 KB) |  | HTML iconHTML  

    X-parameter technology provides simulation-based design of non-linear circuits with inherent accuracy that is attributed to measurement-based model extraction. Recent advancements have combined Non-linear Vector Network Analyzer measurements with impedance tuners to compliment the equivalent accuracy of load-pull measurements with the analytic convenience of equation-based large-signal models. This paper investigates the challenges incurred when modeling high-power transistors under variable complex impedance matching conditions. It also compares the predicted performance of the X-parameter model against an independent large-signal model provided by the manufacturer for a 10W transistor. The results show a good correlation between the two models when compared under load-pull impedance modulation. View full abstract»

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  • Time reference for measurements of arbitrarily shaped pulses

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (435 KB) |  | HTML iconHTML  

    This paper addresses measurements of relative timing of irregularly and differently shaped pulses (by which we mean signals that are zero beyond a finite interval). For such pulses the usual time reference points become useless: rising edges may change their slopes and shapes, and maxima might split. We propose a definition of the time reference applicable to smooth but otherwise arbitrary pulses. It is applicable to signal scaling, simplifies the covariance matrix (of parameters' error estimates) and yields an effective analytic estimate of timing error. View full abstract»

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  • Analysis of phase noise effect on microwave attenuation precision measurement using a heterodyne receiver

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    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (530 KB) |  | HTML iconHTML  

    The phase noise effect on microwave attenuation precision measurement using a lock-in amplifier (LIA) is studied. A frequency domain phase noise modeling is used to analyse the phase sensitive detection made by the LIA. The error bound for the magnitude and phase of LIA measurement has been established. The theoretical prediction of the maximum magnitude and phase fluctuation in LIA output agrees with the measured data quite well. This analysis is important for estimating the maximum attenuation measurement error caused by the phase noise of microwave sources and its uncertainty contribution to microwave attenuation measurement. View full abstract»

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