Second- and Third-Order Signal Predistortion for Nonlinear Distortion Suppression in a TWT

Singh, A.; Scharer, J.E.; Booske, John H.; Wohlbier, J.G.

doi:10.1109/ted.2005.845794

Cited by 22 publications

(11 citation statements)

References 21 publications

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“…Note that the amplitude and phase of this 2ω 0 output are completely controlled by the input signal, which is at the fundamental frequency ω 0 . This second harmonic may also be suppressed by injecting a 2ω 0 signal with an appropriate amplitude and phase [8]. The new insight, together with higher harmonic generation, will be explored in future study.…”

Section: Discussionmentioning

confidence: 99%

Harmonic Content in the Beam Current in a Traveling-Wave Tube

Dong

Zhang

Chernin

et al. 2015

IEEE Trans. Electron Devices

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In a klystron, charge overtaking of electrons leads to an infinity of ac current on the electron beam. This paper extends the klystron theory of orbital bunching to a travelingwave tube (TWT). We calculate the harmonic content of the beam current in a TWT that results from an input signal of a single frequency. We assume that the electron orbits are governed by Pierce's classical three-wave, linear theory. The crowding of these linear orbits may lead to charge overtaking and, therefore, harmonic generation on the beam current, as in a klystron. We analytically calculate the buildup of harmonic content as a function of tube length from the input, and compare the results with the CHRISTINE code. Good agreement is found. Also found is the surprisingly high level of harmonic contents in the electron beam current, even when the TWT operates in the small signal regime. A dimensionless bunching parameter for a TWT, X = (2 P in /( P b C)) 1/2 , is identified, which characterizes the harmonic content in the ac beam current, where P in is the input power of the signal, P b is the dc beam power, and C is Pierce's gain parameter.

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Section: Discussionmentioning

confidence: 99%

Harmonic Content in the Beam Current in a Traveling-Wave Tube

Dong

Zhang

Chernin

et al. 2015

IEEE Trans. Electron Devices

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“…Similarly, signal injection [4] has been proved to be another valid method to suppress the IMD, but most of the related works published in prior literatures are limited in the analog domain and merely aim at removing the intra-band distortion. Aidin et al [2] firstly introduced the signal injection method to restrain the inter-band distortion in the digital domain, but the two injecting IMD signals are fixed with equal magnitude and 180ﾟ degree phase shift compared to the inter-band IMD product terms, so that it is difficult to ensure the inter-band distortion of the transmitter can be well mitigated when nonlinear device and circuit parameters change.…”

Section: Introductionmentioning

confidence: 99%

“…4) Compare the current fitness value of each particle with its best position ever experienced. If the current fitness is smaller, store the current position and fitness into pbest.…”

Section: Introductionmentioning

confidence: 99%

A new signal injection method with PSO for multi-carrier predistortion

Wang

et al. 2013

IEICE Electron. Express

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In multi-carrier transmitters, nonlinear characteristic of power amplifiers (PAs) results in intra-band distortion and interband distortion. The intra-band distortion exists in most singlecarrier transmitters as well, and can be removed by traditional digital predistortion (DPD) techniques. However, the inter-band distortion is rather unique for the multi-carrier linearization. A channel-selective multi-cell DPD architecture which deals with the intra-band and inter-band distortion separately is used in this paper. Furthermore, a new signal injection method with particle swarm optimization (PSO) is proposed to suppress the inter-band distortion in the paper. The injected inter-band signals are firstly reconstructed by a memory polynomial DPD, and then their amplitude and phase are fine-tuned by a PSO algorithm. Simulation results show that the method restrains inter-band distortion significantly and accelerates the convergence speed of PSO algorithm.

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“…The theoretical analyses of harmonic generation and suppression are demonstrated in [7][8][9][10]. Experimental investigation of harmonic suppression is presented in [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

SIMULATION MODELING ON DISPERSION SHAPING AND HARMONIC SUPPRESSION IN HELIX TWT FROM 2 GHz TO 6 GHz

Wei¹

2012

PIER C

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Abstract-This paper describes the investigation of broadband interaction and harmonic suppression. A special dispersion shape used in broadband traveling-wave tubes (TWT) is obtained. The theoretical and simulation studies of negative dispersion are presented. On the basis of these studies, a broadband TWT used in microwave power module (MPM) is designed. Compared with the old TWT with flat dispersion, the new one with negative dispersion decreases the second harmonic content about 10 dB and improves the fundamental efficiency with a maximum increase of about 5% at the lowest frequency 2 GHz. The new one operates with the beam voltage of 3600 V and current of 250 mA. The modified TWT is fabricated and the simulation results meet the measurements very well.

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Second- and Third-Order Signal Predistortion for Nonlinear Distortion Suppression in a TWT

Cited by 22 publications

References 21 publications

Harmonic Content in the Beam Current in a Traveling-Wave Tube

Harmonic Content in the Beam Current in a Traveling-Wave Tube

A new signal injection method with PSO for multi-carrier predistortion

SIMULATION MODELING ON DISPERSION SHAPING AND HARMONIC SUPPRESSION IN HELIX TWT FROM 2 GHz TO 6 GHz

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