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Mahdi Majidi Abbas Mohammadi Abdolali Abdipour 《Analog Integrated Circuits and Signal Processing》2013,74(2):425-437
In this paper we present an exact analytical expression to calculate the spectral regrowth at the output of a nonlinear power amplifier (PA) using the higher order cumulants and Poisson summation formula. This PA is driven by the filtered digitally modulated signals. To improve the accuracy of the calculations, the cyclosationarity of the input signal is considered. Moreover, closed-form expressions for the 1-dB compression and saturation points are extracted as a function of the PA model parameters, higher order statistics of the input signal, and the transfer function of the pulse shaping filter. In addition, an analytical expression for the adjacent channel power (ACP) and a closed-form expression of the ACP ratio are derived. This is followed by investigation of the effect of the PA nonlinearity on the performance of receiver. Simulation studies are carried out to verify the accuracy of the derived expressions. Excellent agreement between the analytical and simulation results is achieved. 相似文献
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非线性调频信号广泛应用于雷达声纳领域,其具有多阶多项式相位、未知参数多的特点,给参数估计带来困难。针对此问题,本文提出一种稀疏重构下的非线性调频信号参数估计算法。该方法利用Gabor原子良好时频特性,以 范数稀疏正则最小二乘模型为目标函数,并推导了问题的二阶锥规划(SOCP)形式,最终通过求解的Gabor原子进行参数估计。算法分析信号的时频特征,完成信号的分解重构,适应于各类调频信号。仿真实验证明,本文算法对调频信号二阶与一阶相位参数估计精度都贴近CRB,而对二阶参数的估计较二次相位差分算法更适应较低信噪比。 相似文献
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A method of spectral analysis for a nonlinear amplifier driven by a Gaussian signal is presented. The technique is based on the Taylor series expansion of the complex gain of an amplifier. Therefore, it takes into account both amplitude-amplitude modulation (AM/AM) and amplitude-phase modulation (AM/PM) conversions and requires only an input signal autocorrelation (or power spectral density) and AM/AM and AM/PM measurements without any additional calculations 相似文献
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A cascode modulated CMOS class-E power amplifier (PA) is presented in this paper. It is shown that by applying a modulated signal to the gate of the cascode transistor the output power is modulated. The main advantage of the proposed technique is a high 35 dB output power dynamic range. The peak power added efficiency (PAE) is 35%. The concept of the cascode power control of class-E RF PA operating at 2.2 GHz with 18 dBm output power was implemented in a CMOS technology and the performance has been verified by measurements. The prototype CMOS PA is tested by single tone excitation and by enhanced data rates for GSM evolution (EDGE) modulated signal. Digital predistortion is used to linearize the transfer characteristic. The EDGE spectrum mask is met and the rms error vector magnitude (EVM) is less than 4° in the entire output power range. 相似文献
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Wireless Networks - Single carrier-frequency division multiple access (SC-FDMA) is a multiple access technique in broadband wireless networks which has been adapted by 3GPP for uplink transmission... 相似文献
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《Electron Devices, IEEE Transactions on》1961,8(4):279-283
In large-diameter electron stream traveling-wave amplifiers there is a significant variation of the circuit electric field across the stream. Most analyses neglect the effects of these field variations. An approximate method has been used to study the effect of transverse field variations on the gain and effciency of large-signal traveling-wave amplifiers. The annular electron stream is subdivided into a number of annular rings each containing an equal fraction of the total current. It is assumed that the circuit field varies over the stream cross section and that each segment has a different coupling to the circuit. The space-charge field is assumed independent of radius. The effect on gain and efficiency is calculated for a stream diameter of B = 1 and it is found that a subdivision of the stream into two segments with different couplings to the circuit gives a lower saturation efficiency but that further subdivision does not appreciably charge the results. 相似文献
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This work presents a fully integrated linearized CMOS RF amplifier, integrated in a 0.18-/spl mu/m CMOS process. The amplifier is implemented on a single chip, requiring no external matching or tuning networks. Peak output power is 27 dBm with a power-added efficiency (PAE) of 34%. The amplitude modulator, implemented on the same chip as the RF amplifier, modulates the supply voltage of the RF amplifier. This results in a power efficient amplification of nonconstant envelope RF signals. The RF power amplifier and amplitude modulator are optimized for the amplification of EDGE signals. The EDGE spectral mask and EVM requirements are met over a wide power range. The maximum EDGE output power is 23.8 dBm and meets the class E3 power requirement of 22 dBm. The corresponding output spectrum at 400 and 600 kHz frequency offset is -59 dB and -70 dB. The EVM has an RMS value of 1.60% and a peak value of 5.87%. 相似文献
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Modulating the dynamics of a nonlinear autoregressive model with a radial basis function (RBF) of exogenous variables is known to reduce the prediction error. Here, RBF is a function that decays to zero exponentially if the deviation between the exogenous variables and a center location becomes large. This paper introduces a class of RBF-based multiplicatively modulated nonlinear autoregressive (mmNAR) models. First, we establish the local asymptotic normality (LAN) for vector conditional heteroscedastic autoregressive nonlinear (CHARN) models, which include the mmNAR and many other well-known time-series models as special cases. Asymptotic optimality for estimation and testing is described in terms of LAN properties. The mmNAR model indicates goodness-of-fit for surface electromyograms (EMG) using electrocorticograms (ECoG) as the exogenous variables. Concretely, it is found that the negative potential of the motor cortex forces change in the frequency of EMG, which is reasonable from a physiological point of view. The proposed mmNAR model fitting is both useful and efficient as a signal-processing technique for extracting information on the action potential, which is associated with the postsynaptic potential. 相似文献
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正交频分复用技术具有较高的频谱效率和好的抗频率选择性衰落性能,被广泛应用于无线通信系统中。但是OFDM信号具有较高的峰均比,当系统采用非线性功放时,OFDM系统需要较大的输入功率回退以避免信号失真。为了研究非线性功放条件下的系统性能,分析了恒包络OFDM系统的实现方式,并以误码率为指标,在加性高斯白噪声信道和多径衰落信道场景下对比了恒包络OFDM系统与采用传统迭代限幅滤波PAPR抑制技术的OFDM系统的性能。 相似文献
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Analysis of nonlinear behavior of power HBTs 总被引:2,自引:0,他引:2
Woonyun Kim Sanghoon Kang Kyungho Lee Minchul Chung Jongchan Kang Bumman Kim 《Microwave Theory and Techniques》2002,50(7):1714-1722
To accurately understand the linear characteristics of a heterojunction bipolar transistor (HBT), we developed an analytical nonlinear HBT model using Volterra-series analysis. The model considers four nonlinear components: rπ, Cdiff, Cdepl, and gm. It shows that nonlinearities of r π and Cdiff are almost completely canceled by g m nonlinearity at all frequencies. The residual gm nonlinearity is highly degenerated by input circuit impedances. Therefore, rπ, Cdiff, Cdepl, and g m nonlinearities generate less harmonics than Cbc nonlinearity. If Cbc is linearized, gm is the main nonlinear source of HBT, and Cdepl becomes very important at a high frequency. The degeneration resistor RE is more effective than RB for reducing gm nonlinearity. This analysis also shows the dependency of the third-order intermodulation (IM3) on the terminations of the source second harmonic impedances. The IM3 of HBT is significantly reduced by setting the second harmonic impedances of ZS,2ω2 = 0 and ZS,ω2-ω1 = 0 相似文献
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Way W.I. Choy M.M. Yi-Yan A. Andrejco M. Saifi M. Lin C. 《Photonics Technology Letters, IEEE》1989,1(10):343-345
The use of an erbium-doped optical fiber power amplifier in a multichannel amplitude-modulated vestigial-sideband CATV transmission system for potential subscriber loop applications is discussed. Using a color-center laser pump at 1.48 μm, a fiber-to-fiber gain of 11.5 dB (at 1.539 μm), which is 10 dB compressed from the small-signal gain, and a total system power margin of 15 dB were achieved. No intermodulation distortion was introduced by the fiber amplifier. The received video SNR of 40-46 dB was limited by the linearity of the distributed-feedback laser diode used 相似文献
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New modified saleh models for memoryless nonlinear power amplifier behavioural modelling 总被引:1,自引:0,他引:1
A new generic modified Saleh (MS) model for use in memoryless nonlinear power amplifier (PA) behavioural modelling is proposed. The model was evolved primarily to overcome some particular weaknesses in the original Saleh model when handling the polar AM-PM envelope modelling. From it new twoparameter MS polar models are derived. By modelling a nearmemoryless LDMOS PA amplifying a WCDMA signal, evidence of the improvement in modelling accuracy and performance of the MS over the original Saleh for both polar and quadrature models is provided. 相似文献
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非对称Doherty功率放大器的研究与设计 总被引:3,自引:0,他引:3
基于传统Doherty功放在实际应用中存在的某些缺陷,提出了一种可用于TD-SCDMA基站功放的非对称Doherty功放结构.输入端应用了不等功率功分器,且主功放和峰值功放的漏极偏压也不同.在一定程度上提高了功放的效率,增加了输出功率. 相似文献
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The statistical properties of Rayleigh backscattering from single-mode fibers are investigated, taking into account the modulation and the coherence of the source light. The autocorrelation function and the power spectral density of the backscattered field and intensity are derived. To describe the noise due to Rayleigh backscattering in bidirectional systems, the spectrum of the interference of backscattered light with reflected source light is also calculated. The measurements confirm the theoretical results. It is shown that, if no optical isolator is used and the laser diode is exposed to Rayleigh backscattering, the interaction between laser and fiber depends strongly on the modulation of the light 相似文献
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For pt.1 see ibid., vol.5, no.1, p.13 (1993). The subject of the paper is the estimation of the spectra of signals and both classical estimation methods and modern model-based methods are discussed. These techniques are compared and results are presented which demonstrate the superior resolution which is obtained with modern autoregressive spectral analysis methods. Examples are given of the application of these techniques in the areas of speech processing and biomedical signal analysis 相似文献