The Experts below are selected from a list of 1056 Experts worldwide ranked by ideXlab platform
M.b. Steer - One of the best experts on this subject based on the ideXlab platform.
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capturing asymmetrical Spectral Regrowth in rf systems using a multislice behavioral model and enhanced envelop transient analysis
International Journal of Rf and Microwave Computer-aided Engineering, 2006Co-Authors: Wonhoon Jang, K.g. Gard, A Walker, M.b. SteerAbstract:Nonlinear distortion in RF and microwave systems results in Spectral Regrowth of digitally modulated signals. The distortion above and below the main channel can be at different levels and this is attributed to baseband effects. This article presents a new multislice behavioral-model architecture that captures this asymmetry and can be implemented in a variety of circuit simulators, including SPICE, harmonic balance (HB), envelope transient (ET), and system simulators. The work is experimentally validated using an HBT power amplifier at 2.5 GHz driven by a WCDMA signal. The model is used with envelope transient circuit simulation which is enhanced to accommodate an arbitrary baseband transfer function. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.
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capturing asymmetrical Spectral Regrowth in rf systems using a multislice behavioral model and enhanced envelop transient analysis research articles
International Journal of Rf and Microwave Computer-aided Engineering, 2006Co-Authors: Wonhoon Jang, K.g. Gard, A Walker, M.b. SteerAbstract:Nonlinear distortion in RF and microwave systems results in Spectral Regrowth of digitally modulated signals. The distortion above and below the main channel can be at different levels and this is attributed to baseband effects. This article presents a new multislice behavioral-model architecture that captures this asymmetry and can be implemented in a variety of circuit simulators, including SPICE, harmonic balance (HB), envelope transient (ET), and system simulators. The work is experimentally validated using an HBT power amplifier at 2.5 GHz driven by a WCDMA signal. The model is used with envelope transient circuit simulation which is enhanced to accommodate an arbitrary baseband transfer function. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.
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statistical analysis of Spectral Regrowth in wireless nonlinear circuits
European Microwave Conference, 2004Co-Authors: K.g. Gard, L.e. Larson, M.b. SteerAbstract:The output power spectrum of a modulated carrier applied to a nonlinear wireless circuit is analyzed using the statistical properties of the signal and a complex power series behavioral model of the nonlinear circuit. Nonlinear analysis of signals with known statistical moment properties results in reduced order expressions for the output power spectrum in terms of the autocorrelation function of the input signal and the power series coefticients. Comparisons are presented for several limiting amplifier models and between measured versus predicted adjacent channel power rejection (ACPR) values for a microwave amplifier.
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the importance of nonlinear order in modeling intermodulation distortion and Spectral Regrowth
IEEE Radio and Wireless Conference, 2002Co-Authors: Khaled M Gharaibeh, K.g. Gard, H. Gutierrez, M.b. SteerAbstract:Modeling of distortion in nonlinear RF and microwave amplifiers requires high order nonlinear modeling to capture behavior with digitally modulated signals but only low order modeling to capture the response with discrete spectra as in two-tone testing. This paper establishes model order requirements for successful behavioral modeling for system explorations.
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generalized autocorrelation analysis of Spectral Regrowth from bandpass nonlinear circuits
International Microwave Symposium, 2001Co-Authors: K.g. Gard, M.b. Steer, L.e. LarsonAbstract:Estimation of Spectral Regrowth generated by a digitally modulated carrier passed through a nonlinear RF circuit is analyzed using a formulation of the output autocorrelation function. The estimation is based on developing an analytical expression for the output power spectrum when the nonlinearity is modeled as a complex power series model extracted from measured amplitude-to-amplitude (AM-AM) and amplitude-to-phase (AM-PM) characteristics. An analytical expression of the output power spectrum is developed from statistical moments for a complex Gaussian input signal. Comparisons are presented of measured versus predicted ACPR values for a CDMA amplifier.
G T Zhou - One of the best experts on this subject based on the ideXlab platform.
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predicting Spectral Regrowth of nonlinear power amplifiers
IEEE Transactions on Communications, 2002Co-Authors: G T Zhou, J S KenneyAbstract:Power amplifiers (PAs) are important elements in communications systems and they are inherently nonlinear. Nonlinearity generates Spectral Regrowth (i.e., Spectral broadening) in digitally modulated signals which causes adjacent channel interference. In this paper, we present a closed-form expression for the auto-covariance function of the PA output, whose Fourier transform yields the output power Spectral density (PSD). The PA input does not need to be Gaussian and the PSD calculation can be carried out using common PA descriptions such as the AM/AM and AM/PM characteristics. We assume that the input is narrow-band, thus PA memory effects, on the order of a symbol period, are not present. The analytical results allow us to predict Spectral Regrowth without running expensive or time-consuming time-domain simulations; they also lead to a variety of optimization possibilities in transmitter design that includes the PAs.
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analyzing Spectral Regrowth of qpsk and oqpsk signals
International Conference on Acoustics Speech and Signal Processing, 2001Co-Authors: Raviv Raich, G T ZhouAbstract:A comparison is made between the Spectral Regrowth of quadrature phase shift keyed (QPSK) and offset QPSK (OQPSK) signals as they go through nonlinear amplifications. Contrary to existing approaches that assume the power amplifier input is Gaussian, our analysis is carried out without the Gaussian assumption, by using higher-order statistics. We show that it is possible to assess quantitatively whether and how much OQPSK is beneficial in reducing Spectral Regrowth. Simple closed form formulas are obtained when the pulse shape filter is time-limited. A particular measure of Spectral broadening is also provided.
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analysis of Spectral Regrowth of weakly nonlinear power amplifiers
IEEE Communications Letters, 2000Co-Authors: G T ZhouAbstract:Power amplifiers (PAs) are important components in a wireless communications system. Linearity and efficiency are two desirable but conflicting requirements, All PAs exhibit varying degrees of nonlinearity which causes Spectral Regrowth and adjacent channel interference. Based on the behavior model of the PA and statistics of the input, it is possible to analyze Spectral Regrowth in the output. Existing results assume that the input is Gaussian whereas our analysis does not. Analytical results on Spectral Regrowth are useful in finding optimal operating conditions of the PA so that maximum efficiency is achieved without violating the out-of-band emission requirement.
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analysis of Spectral Regrowth of weakly nonlinear power amplifiers
International Conference on Acoustics Speech and Signal Processing, 2000Co-Authors: G T ZhouAbstract:Power amplifiers (PAs) are important components in a wireless communications system. Linearity and efficiency are two desirable but conflicting requirements of a PA. All PAs exhibit varying degrees of nonlinearity which causes Spectral Regrowth and adjacent channel interference. Based on the behavior model of the PA and statistics of the input, it is possible to infer Spectral Regrowth in the output. Existing analytical results on Spectral Regrowth assume that the input is Gaussian, which is unrealistic for many digital communications signals. We derive a closed form expression between the covariance function (and hence the power spectrum) of the output and statistics of the input, based on a polynomial behavior model of the PA, without assuming that the input is Gaussian. Such analytical results are useful in finding optimal operating conditions of the PA so that maximum efficiency is achieved without violating the out-of-band emission requirement.
L.e. Larson - One of the best experts on this subject based on the ideXlab platform.
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analysis of envelope signal injection for improvement of rf amplifier intermodulation distortion
IEEE Journal of Solid-state Circuits, 2005Co-Authors: Vincent W Leung, Junxiong Deng, Prasad S Gudem, L.e. LarsonAbstract:Adaptive bias techniques based on envelope signal power detection have been proposed for linearity enhancement and dc current reduction in RF amplifiers. Experimental results show an improvement in amplifier linearity, although asymmetric intermodulation distortion (IMD) was observed. This work rigorously studies the effects of the envelope signal injection on amplifier distortion using the Volterra series formulations. The results intuitively explain the Spectral Regrowth asymmetry, and point to a design technique in which third-order IMD can be optimally cancelled. The theory was verified through comparison to measurement and simulation results.
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nonlinearity estimation and Spectral Regrowth prediction of power amplifiers using correlation techniques
Wireless and Microwave Technology Conference, 2005Co-Authors: I Galton, L.e. Larson, P M AsbeckAbstract:Nonlinearity estimation and Spectral Regrowth prediction are crucial to power amplifier linearization. The correlation techniques shown here can estimate amplifier nonlinearity and predict out-of-band power spectrum. Cross-correlation is performed between the output envelope and a test sequence generated from the input signal and can be carried out in background during amplifier operations. The proposed method is applicable to multi-channel DS-CDMA systems and IS-95 forward-link CDMA signals are employed as an example.
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The impact of RF front-end characteristics on the Spectral Regrowth of communications signals
IEEE Transactions on Microwave Theory and Techniques, 2005Co-Authors: Kevin G. Gard, L.e. Larson, Michael B. SteerAbstract:The nonlinear characteristic of an RF front-end results in in-band distortion and Spectral Regrowth of digitally modulated signals with distortion being dependent on the statistical variation of the signal. In this paper, the interaction of the nonlinear response with the signal is explored using a time-averaged autocorrelation analysis applied to several limiter-amplifier models having characteristics ranging from soft-to-hard amplitude limiting. The analysis is verified by comparing measured and predicted adjacent channel power rejection for a code-division multiple-access amplifier.
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statistical analysis of Spectral Regrowth in wireless nonlinear circuits
European Microwave Conference, 2004Co-Authors: K.g. Gard, L.e. Larson, M.b. SteerAbstract:The output power spectrum of a modulated carrier applied to a nonlinear wireless circuit is analyzed using the statistical properties of the signal and a complex power series behavioral model of the nonlinear circuit. Nonlinear analysis of signals with known statistical moment properties results in reduced order expressions for the output power spectrum in terms of the autocorrelation function of the input signal and the power series coefticients. Comparisons are presented for several limiting amplifier models and between measured versus predicted adjacent channel power rejection (ACPR) values for a microwave amplifier.
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generalized autocorrelation analysis of Spectral Regrowth from bandpass nonlinear circuits
International Microwave Symposium, 2001Co-Authors: K.g. Gard, M.b. Steer, L.e. LarsonAbstract:Estimation of Spectral Regrowth generated by a digitally modulated carrier passed through a nonlinear RF circuit is analyzed using a formulation of the output autocorrelation function. The estimation is based on developing an analytical expression for the output power spectrum when the nonlinearity is modeled as a complex power series model extracted from measured amplitude-to-amplitude (AM-AM) and amplitude-to-phase (AM-PM) characteristics. An analytical expression of the output power spectrum is developed from statistical moments for a complex Gaussian input signal. Comparisons are presented of measured versus predicted ACPR values for a CDMA amplifier.
Michael B. Steer - One of the best experts on this subject based on the ideXlab platform.
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The impact of RF front-end characteristics on the Spectral Regrowth of communications signals
IEEE Transactions on Microwave Theory and Techniques, 2005Co-Authors: Kevin G. Gard, L.e. Larson, Michael B. SteerAbstract:The nonlinear characteristic of an RF front-end results in in-band distortion and Spectral Regrowth of digitally modulated signals with distortion being dependent on the statistical variation of the signal. In this paper, the interaction of the nonlinear response with the signal is explored using a time-averaged autocorrelation analysis applied to several limiter-amplifier models having characteristics ranging from soft-to-hard amplitude limiting. The analysis is verified by comparing measured and predicted adjacent channel power rejection for a code-division multiple-access amplifier.
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On the significance of envelope peak-to-average ratio for estimating the Spectral Regrowth of an RF/microwave power amplifier
IEEE Transactions on Microwave Theory and Techniques, 2000Co-Authors: John F. Sevic, Michael B. SteerAbstract:The peak-to-average ratio (PAR) of a signal is commonly used for estimating the backoff required for an radio-frequency/microwave power amplifier to exhibit acceptable intermodulation distortion. In this paper, it is shown that the PAR is an inaccurate metric for predicting the backoff and can lead to improper choices for modulation with respect to the linearity-efficiency tradeoff. A specific case is presented, based on the IS-94 code-division multiple-access communication (CDMA) reverse-link and IS-95 CDMA forward-link wireless standards. Using simulation and load-pull measurements, it is illustrated that although quaternary phase-shift keying has a higher PAR than offset QPSK (O-QPSK), it has lower adjacent-channel power, for constant average power. This observation, contrary to what is expected, is explained by introducing the envelope distribution function, which characterizes the saturation of an amplifier based on the time-domain statistics of the applied signal.
K.g. Gard - One of the best experts on this subject based on the ideXlab platform.
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capturing asymmetrical Spectral Regrowth in rf systems using a multislice behavioral model and enhanced envelop transient analysis research articles
International Journal of Rf and Microwave Computer-aided Engineering, 2006Co-Authors: Wonhoon Jang, K.g. Gard, A Walker, M.b. SteerAbstract:Nonlinear distortion in RF and microwave systems results in Spectral Regrowth of digitally modulated signals. The distortion above and below the main channel can be at different levels and this is attributed to baseband effects. This article presents a new multislice behavioral-model architecture that captures this asymmetry and can be implemented in a variety of circuit simulators, including SPICE, harmonic balance (HB), envelope transient (ET), and system simulators. The work is experimentally validated using an HBT power amplifier at 2.5 GHz driven by a WCDMA signal. The model is used with envelope transient circuit simulation which is enhanced to accommodate an arbitrary baseband transfer function. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.
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capturing asymmetrical Spectral Regrowth in rf systems using a multislice behavioral model and enhanced envelop transient analysis
International Journal of Rf and Microwave Computer-aided Engineering, 2006Co-Authors: Wonhoon Jang, K.g. Gard, A Walker, M.b. SteerAbstract:Nonlinear distortion in RF and microwave systems results in Spectral Regrowth of digitally modulated signals. The distortion above and below the main channel can be at different levels and this is attributed to baseband effects. This article presents a new multislice behavioral-model architecture that captures this asymmetry and can be implemented in a variety of circuit simulators, including SPICE, harmonic balance (HB), envelope transient (ET), and system simulators. The work is experimentally validated using an HBT power amplifier at 2.5 GHz driven by a WCDMA signal. The model is used with envelope transient circuit simulation which is enhanced to accommodate an arbitrary baseband transfer function. © 2006 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2006.
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statistical analysis of Spectral Regrowth in wireless nonlinear circuits
European Microwave Conference, 2004Co-Authors: K.g. Gard, L.e. Larson, M.b. SteerAbstract:The output power spectrum of a modulated carrier applied to a nonlinear wireless circuit is analyzed using the statistical properties of the signal and a complex power series behavioral model of the nonlinear circuit. Nonlinear analysis of signals with known statistical moment properties results in reduced order expressions for the output power spectrum in terms of the autocorrelation function of the input signal and the power series coefticients. Comparisons are presented for several limiting amplifier models and between measured versus predicted adjacent channel power rejection (ACPR) values for a microwave amplifier.
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the importance of nonlinear order in modeling intermodulation distortion and Spectral Regrowth
IEEE Radio and Wireless Conference, 2002Co-Authors: Khaled M Gharaibeh, K.g. Gard, H. Gutierrez, M.b. SteerAbstract:Modeling of distortion in nonlinear RF and microwave amplifiers requires high order nonlinear modeling to capture behavior with digitally modulated signals but only low order modeling to capture the response with discrete spectra as in two-tone testing. This paper establishes model order requirements for successful behavioral modeling for system explorations.
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generalized autocorrelation analysis of Spectral Regrowth from bandpass nonlinear circuits
International Microwave Symposium, 2001Co-Authors: K.g. Gard, M.b. Steer, L.e. LarsonAbstract:Estimation of Spectral Regrowth generated by a digitally modulated carrier passed through a nonlinear RF circuit is analyzed using a formulation of the output autocorrelation function. The estimation is based on developing an analytical expression for the output power spectrum when the nonlinearity is modeled as a complex power series model extracted from measured amplitude-to-amplitude (AM-AM) and amplitude-to-phase (AM-PM) characteristics. An analytical expression of the output power spectrum is developed from statistical moments for a complex Gaussian input signal. Comparisons are presented of measured versus predicted ACPR values for a CDMA amplifier.
